From 8219d92987c7d9641d6b24c4d5be29e3a80fd6b9 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Tue, 22 Dec 2020 19:25:24 -0700
Subject: [PATCH] stage2: fix Cache deadlock and build more of TSAN

 * rename is_compiler_rt_or_libc to skip_linker_dependencies
   and set it to `true` for all sub-Compilations. I believe
   this resolves the deadlock we were experiencing on Drone
   CI and on some users' computers. I will remove the CI workaround in
   a follow-up commit.
 * enabling TSAN automatically causes the Compilation to link against
   libc++ even if not requested, because TSAN depends on libc++.
 * add -fno-rtti flags where appropriate when building TSAN objects.
   Thanks Firefox317 for pointing this out.
 * TSAN support: resolve all the undefined symbols. We are still seeing
   a dependency on __gcc_personality_v0 but will resolve this one in a
   follow-up commit.
 * static libs do not try to build libc++ or libc++abi.
---
 lib/tsan/interception/interception_linux.cpp  |   83 ++
 lib/tsan/interception/interception_mac.cpp    |   18 +
 .../interception/interception_type_test.cpp   |   39 +
 lib/tsan/interception/interception_win.cpp    | 1022 +++++++++++++++++
 .../sanitizer_allocator_checks.cpp            |   22 +
 .../sanitizer_allocator_report.cpp            |  137 +++
 .../sanitizer_common_libcdep.cpp              |  149 +++
 .../sanitizer_common_nolibc.cpp               |   34 +
 .../sanitizer_linux_libcdep.cpp               |  846 ++++++++++++++
 .../sanitizer_mac_libcdep.cpp                 |   29 +
 .../sanitizer_posix_libcdep.cpp               |  509 ++++++++
 .../sanitizer_common/sanitizer_stackdepot.cpp |  149 +++
 .../sanitizer_common/sanitizer_stacktrace.cpp |  133 +++
 .../sanitizer_stacktrace_libcdep.cpp          |  159 +++
 .../sanitizer_stacktrace_printer.cpp          |  263 +++++
 .../sanitizer_stacktrace_sparc.cpp            |   85 ++
 .../sanitizer_stoptheworld_linux_libcdep.cpp  |  573 +++++++++
 .../sanitizer_stoptheworld_netbsd_libcdep.cpp |  364 ++++++
 .../sanitizer_common/sanitizer_symbolizer.cpp |  135 +++
 .../sanitizer_symbolizer_libbacktrace.cpp     |  209 ++++
 .../sanitizer_symbolizer_libcdep.cpp          |  554 +++++++++
 .../sanitizer_symbolizer_mac.cpp              |  249 ++++
 .../sanitizer_symbolizer_markup.cpp           |  146 +++
 .../sanitizer_symbolizer_posix_libcdep.cpp    |  492 ++++++++
 .../sanitizer_symbolizer_report.cpp           |  293 +++++
 .../sanitizer_symbolizer_win.cpp              |  318 +++++
 .../sanitizer_unwind_linux_libcdep.cpp        |  180 +++
 .../sanitizer_common/sanitizer_unwind_win.cpp |   75 ++
 lib/tsan/tsan_interceptors_mac.cpp            |  519 +++++++++
 lib/tsan/tsan_interceptors_mach_vm.cpp        |   52 +
 lib/tsan/tsan_platform_linux.cpp              |  517 +++++++++
 lib/tsan/tsan_platform_mac.cpp                |  324 ++++++
 lib/tsan/tsan_platform_posix.cpp              |  167 +++
 lib/tsan/tsan_rtl_aarch64.S                   |  245 ++++
 lib/tsan/tsan_rtl_amd64.S                     |  366 ++++++
 lib/tsan/tsan_rtl_mips64.S                    |  214 ++++
 lib/tsan/tsan_rtl_ppc64.S                     |  288 +++++
 src/Compilation.zig                           |   33 +-
 src/glibc.zig                                 |    2 +-
 src/libcxx.zig                                |    2 +
 src/libtsan.zig                               |  198 +++-
 src/libunwind.zig                             |    1 +
 src/link.zig                                  |    2 +-
 src/link/Coff.zig                             |    4 +-
 src/link/Elf.zig                              |    6 +-
 src/link/MachO.zig                            |    4 +-
 src/link/Wasm.zig                             |    2 +-
 src/musl.zig                                  |    2 +-
 48 files changed, 10172 insertions(+), 41 deletions(-)
 create mode 100644 lib/tsan/interception/interception_linux.cpp
 create mode 100644 lib/tsan/interception/interception_mac.cpp
 create mode 100644 lib/tsan/interception/interception_type_test.cpp
 create mode 100644 lib/tsan/interception/interception_win.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_allocator_checks.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_allocator_report.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_common_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_common_nolibc.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_linux_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_mac_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_posix_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_stackdepot.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_stacktrace.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_stacktrace_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_stacktrace_printer.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_stacktrace_sparc.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_stoptheworld_netbsd_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_symbolizer.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_symbolizer_libbacktrace.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_symbolizer_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_symbolizer_mac.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_symbolizer_markup.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_symbolizer_report.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_symbolizer_win.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp
 create mode 100644 lib/tsan/sanitizer_common/sanitizer_unwind_win.cpp
 create mode 100644 lib/tsan/tsan_interceptors_mac.cpp
 create mode 100644 lib/tsan/tsan_interceptors_mach_vm.cpp
 create mode 100644 lib/tsan/tsan_platform_linux.cpp
 create mode 100644 lib/tsan/tsan_platform_mac.cpp
 create mode 100644 lib/tsan/tsan_platform_posix.cpp
 create mode 100644 lib/tsan/tsan_rtl_aarch64.S
 create mode 100644 lib/tsan/tsan_rtl_amd64.S
 create mode 100644 lib/tsan/tsan_rtl_mips64.S
 create mode 100644 lib/tsan/tsan_rtl_ppc64.S

diff --git a/lib/tsan/interception/interception_linux.cpp b/lib/tsan/interception/interception_linux.cpp
new file mode 100644
index 0000000000..950cd51265
--- /dev/null
+++ b/lib/tsan/interception/interception_linux.cpp
@@ -0,0 +1,83 @@
+//===-- interception_linux.cpp ----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// Linux-specific interception methods.
+//===----------------------------------------------------------------------===//
+
+#include "interception.h"
+
+#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
+
+#include <dlfcn.h>   // for dlsym() and dlvsym()
+
+namespace __interception {
+
+#if SANITIZER_NETBSD
+static int StrCmp(const char *s1, const char *s2) {
+  while (true) {
+    if (*s1 != *s2)
+      return false;
+    if (*s1 == 0)
+      return true;
+    s1++;
+    s2++;
+  }
+}
+#endif
+
+static void *GetFuncAddr(const char *name, uptr wrapper_addr) {
+#if SANITIZER_NETBSD
+  // FIXME: Find a better way to handle renames
+  if (StrCmp(name, "sigaction"))
+    name = "__sigaction14";
+#endif
+  void *addr = dlsym(RTLD_NEXT, name);
+  if (!addr) {
+    // If the lookup using RTLD_NEXT failed, the sanitizer runtime library is
+    // later in the library search order than the DSO that we are trying to
+    // intercept, which means that we cannot intercept this function. We still
+    // want the address of the real definition, though, so look it up using
+    // RTLD_DEFAULT.
+    addr = dlsym(RTLD_DEFAULT, name);
+
+    // In case `name' is not loaded, dlsym ends up finding the actual wrapper.
+    // We don't want to intercept the wrapper and have it point to itself.
+    if ((uptr)addr == wrapper_addr)
+      addr = nullptr;
+  }
+  return addr;
+}
+
+bool InterceptFunction(const char *name, uptr *ptr_to_real, uptr func,
+                       uptr wrapper) {
+  void *addr = GetFuncAddr(name, wrapper);
+  *ptr_to_real = (uptr)addr;
+  return addr && (func == wrapper);
+}
+
+// Android and Solaris do not have dlvsym
+#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS && !SANITIZER_OPENBSD
+static void *GetFuncAddr(const char *name, const char *ver) {
+  return dlvsym(RTLD_NEXT, name, ver);
+}
+
+bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
+                       uptr func, uptr wrapper) {
+  void *addr = GetFuncAddr(name, ver);
+  *ptr_to_real = (uptr)addr;
+  return addr && (func == wrapper);
+}
+#endif  // !SANITIZER_ANDROID
+
+}  // namespace __interception
+
+#endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
+        // SANITIZER_OPENBSD || SANITIZER_SOLARIS
diff --git a/lib/tsan/interception/interception_mac.cpp b/lib/tsan/interception/interception_mac.cpp
new file mode 100644
index 0000000000..fb6eadcff5
--- /dev/null
+++ b/lib/tsan/interception/interception_mac.cpp
@@ -0,0 +1,18 @@
+//===-- interception_mac.cpp ------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// Mac-specific interception methods.
+//===----------------------------------------------------------------------===//
+
+#include "interception.h"
+
+#if SANITIZER_MAC
+
+#endif  // SANITIZER_MAC
diff --git a/lib/tsan/interception/interception_type_test.cpp b/lib/tsan/interception/interception_type_test.cpp
new file mode 100644
index 0000000000..a611604a70
--- /dev/null
+++ b/lib/tsan/interception/interception_type_test.cpp
@@ -0,0 +1,39 @@
+//===-- interception_type_test.cpp ------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// Compile-time tests of the internal type definitions.
+//===----------------------------------------------------------------------===//
+
+#include "interception.h"
+
+#if SANITIZER_LINUX || SANITIZER_MAC
+
+#include <sys/types.h>
+#include <stddef.h>
+#include <stdint.h>
+
+COMPILER_CHECK(sizeof(::SIZE_T) == sizeof(size_t));
+COMPILER_CHECK(sizeof(::SSIZE_T) == sizeof(ssize_t));
+COMPILER_CHECK(sizeof(::PTRDIFF_T) == sizeof(ptrdiff_t));
+COMPILER_CHECK(sizeof(::INTMAX_T) == sizeof(intmax_t));
+
+#if !SANITIZER_MAC
+COMPILER_CHECK(sizeof(::OFF64_T) == sizeof(off64_t));
+#endif
+
+// The following are the cases when pread (and friends) is used instead of
+// pread64. In those cases we need OFF_T to match off_t. We don't care about the
+// rest (they depend on _FILE_OFFSET_BITS setting when building an application).
+# if SANITIZER_ANDROID || !defined _FILE_OFFSET_BITS || \
+  _FILE_OFFSET_BITS != 64
+COMPILER_CHECK(sizeof(::OFF_T) == sizeof(off_t));
+# endif
+
+#endif
diff --git a/lib/tsan/interception/interception_win.cpp b/lib/tsan/interception/interception_win.cpp
new file mode 100644
index 0000000000..1a1c327e61
--- /dev/null
+++ b/lib/tsan/interception/interception_win.cpp
@@ -0,0 +1,1022 @@
+//===-- interception_linux.cpp ----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// Windows-specific interception methods.
+//
+// This file is implementing several hooking techniques to intercept calls
+// to functions. The hooks are dynamically installed by modifying the assembly
+// code.
+//
+// The hooking techniques are making assumptions on the way the code is
+// generated and are safe under these assumptions.
+//
+// On 64-bit architecture, there is no direct 64-bit jump instruction. To allow
+// arbitrary branching on the whole memory space, the notion of trampoline
+// region is used. A trampoline region is a memory space withing 2G boundary
+// where it is safe to add custom assembly code to build 64-bit jumps.
+//
+// Hooking techniques
+// ==================
+//
+// 1) Detour
+//
+//    The Detour hooking technique is assuming the presence of an header with
+//    padding and an overridable 2-bytes nop instruction (mov edi, edi). The
+//    nop instruction can safely be replaced by a 2-bytes jump without any need
+//    to save the instruction. A jump to the target is encoded in the function
+//    header and the nop instruction is replaced by a short jump to the header.
+//
+//        head:  5 x nop                 head:  jmp <hook>
+//        func:  mov edi, edi    -->     func:  jmp short <head>
+//               [...]                   real:  [...]
+//
+//    This technique is only implemented on 32-bit architecture.
+//    Most of the time, Windows API are hookable with the detour technique.
+//
+// 2) Redirect Jump
+//
+//    The redirect jump is applicable when the first instruction is a direct
+//    jump. The instruction is replaced by jump to the hook.
+//
+//        func:  jmp <label>     -->     func:  jmp <hook>
+//
+//    On an 64-bit architecture, a trampoline is inserted.
+//
+//        func:  jmp <label>     -->     func:  jmp <tramp>
+//                                              [...]
+//
+//                                   [trampoline]
+//                                      tramp:  jmp QWORD [addr]
+//                                       addr:  .bytes <hook>
+//
+//    Note: <real> is equilavent to <label>.
+//
+// 3) HotPatch
+//
+//    The HotPatch hooking is assuming the presence of an header with padding
+//    and a first instruction with at least 2-bytes.
+//
+//    The reason to enforce the 2-bytes limitation is to provide the minimal
+//    space to encode a short jump. HotPatch technique is only rewriting one
+//    instruction to avoid breaking a sequence of instructions containing a
+//    branching target.
+//
+//    Assumptions are enforced by MSVC compiler by using the /HOTPATCH flag.
+//      see: https://msdn.microsoft.com/en-us/library/ms173507.aspx
+//    Default padding length is 5 bytes in 32-bits and 6 bytes in 64-bits.
+//
+//        head:   5 x nop                head:  jmp <hook>
+//        func:   <instr>        -->     func:  jmp short <head>
+//                [...]                  body:  [...]
+//
+//                                   [trampoline]
+//                                       real:  <instr>
+//                                              jmp <body>
+//
+//    On an 64-bit architecture:
+//
+//        head:   6 x nop                head:  jmp QWORD [addr1]
+//        func:   <instr>        -->     func:  jmp short <head>
+//                [...]                  body:  [...]
+//
+//                                   [trampoline]
+//                                      addr1:  .bytes <hook>
+//                                       real:  <instr>
+//                                              jmp QWORD [addr2]
+//                                      addr2:  .bytes <body>
+//
+// 4) Trampoline
+//
+//    The Trampoline hooking technique is the most aggressive one. It is
+//    assuming that there is a sequence of instructions that can be safely
+//    replaced by a jump (enough room and no incoming branches).
+//
+//    Unfortunately, these assumptions can't be safely presumed and code may
+//    be broken after hooking.
+//
+//        func:   <instr>        -->     func:  jmp <hook>
+//                <instr>
+//                [...]                  body:  [...]
+//
+//                                   [trampoline]
+//                                       real:  <instr>
+//                                              <instr>
+//                                              jmp <body>
+//
+//    On an 64-bit architecture:
+//
+//        func:   <instr>        -->     func:  jmp QWORD [addr1]
+//                <instr>
+//                [...]                  body:  [...]
+//
+//                                   [trampoline]
+//                                      addr1:  .bytes <hook>
+//                                       real:  <instr>
+//                                              <instr>
+//                                              jmp QWORD [addr2]
+//                                      addr2:  .bytes <body>
+//===----------------------------------------------------------------------===//
+
+#include "interception.h"
+
+#if SANITIZER_WINDOWS
+#include "sanitizer_common/sanitizer_platform.h"
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+namespace __interception {
+
+static const int kAddressLength = FIRST_32_SECOND_64(4, 8);
+static const int kJumpInstructionLength = 5;
+static const int kShortJumpInstructionLength = 2;
+static const int kIndirectJumpInstructionLength = 6;
+static const int kBranchLength =
+    FIRST_32_SECOND_64(kJumpInstructionLength, kIndirectJumpInstructionLength);
+static const int kDirectBranchLength = kBranchLength + kAddressLength;
+
+static void InterceptionFailed() {
+  // Do we have a good way to abort with an error message here?
+  __debugbreak();
+}
+
+static bool DistanceIsWithin2Gig(uptr from, uptr target) {
+#if SANITIZER_WINDOWS64
+  if (from < target)
+    return target - from <= (uptr)0x7FFFFFFFU;
+  else
+    return from - target <= (uptr)0x80000000U;
+#else
+  // In a 32-bit address space, the address calculation will wrap, so this check
+  // is unnecessary.
+  return true;
+#endif
+}
+
+static uptr GetMmapGranularity() {
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  return si.dwAllocationGranularity;
+}
+
+static uptr RoundUpTo(uptr size, uptr boundary) {
+  return (size + boundary - 1) & ~(boundary - 1);
+}
+
+// FIXME: internal_str* and internal_mem* functions should be moved from the
+// ASan sources into interception/.
+
+static size_t _strlen(const char *str) {
+  const char* p = str;
+  while (*p != '\0') ++p;
+  return p - str;
+}
+
+static char* _strchr(char* str, char c) {
+  while (*str) {
+    if (*str == c)
+      return str;
+    ++str;
+  }
+  return nullptr;
+}
+
+static void _memset(void *p, int value, size_t sz) {
+  for (size_t i = 0; i < sz; ++i)
+    ((char*)p)[i] = (char)value;
+}
+
+static void _memcpy(void *dst, void *src, size_t sz) {
+  char *dst_c = (char*)dst,
+       *src_c = (char*)src;
+  for (size_t i = 0; i < sz; ++i)
+    dst_c[i] = src_c[i];
+}
+
+static bool ChangeMemoryProtection(
+    uptr address, uptr size, DWORD *old_protection) {
+  return ::VirtualProtect((void*)address, size,
+                          PAGE_EXECUTE_READWRITE,
+                          old_protection) != FALSE;
+}
+
+static bool RestoreMemoryProtection(
+    uptr address, uptr size, DWORD old_protection) {
+  DWORD unused;
+  return ::VirtualProtect((void*)address, size,
+                          old_protection,
+                          &unused) != FALSE;
+}
+
+static bool IsMemoryPadding(uptr address, uptr size) {
+  u8* function = (u8*)address;
+  for (size_t i = 0; i < size; ++i)
+    if (function[i] != 0x90 && function[i] != 0xCC)
+      return false;
+  return true;
+}
+
+static const u8 kHintNop8Bytes[] = {
+  0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+template<class T>
+static bool FunctionHasPrefix(uptr address, const T &pattern) {
+  u8* function = (u8*)address - sizeof(pattern);
+  for (size_t i = 0; i < sizeof(pattern); ++i)
+    if (function[i] != pattern[i])
+      return false;
+  return true;
+}
+
+static bool FunctionHasPadding(uptr address, uptr size) {
+  if (IsMemoryPadding(address - size, size))
+    return true;
+  if (size <= sizeof(kHintNop8Bytes) &&
+      FunctionHasPrefix(address, kHintNop8Bytes))
+    return true;
+  return false;
+}
+
+static void WritePadding(uptr from, uptr size) {
+  _memset((void*)from, 0xCC, (size_t)size);
+}
+
+static void WriteJumpInstruction(uptr from, uptr target) {
+  if (!DistanceIsWithin2Gig(from + kJumpInstructionLength, target))
+    InterceptionFailed();
+  ptrdiff_t offset = target - from - kJumpInstructionLength;
+  *(u8*)from = 0xE9;
+  *(u32*)(from + 1) = offset;
+}
+
+static void WriteShortJumpInstruction(uptr from, uptr target) {
+  sptr offset = target - from - kShortJumpInstructionLength;
+  if (offset < -128 || offset > 127)
+    InterceptionFailed();
+  *(u8*)from = 0xEB;
+  *(u8*)(from + 1) = (u8)offset;
+}
+
+#if SANITIZER_WINDOWS64
+static void WriteIndirectJumpInstruction(uptr from, uptr indirect_target) {
+  // jmp [rip + <offset>] = FF 25 <offset> where <offset> is a relative
+  // offset.
+  // The offset is the distance from then end of the jump instruction to the
+  // memory location containing the targeted address. The displacement is still
+  // 32-bit in x64, so indirect_target must be located within +/- 2GB range.
+  int offset = indirect_target - from - kIndirectJumpInstructionLength;
+  if (!DistanceIsWithin2Gig(from + kIndirectJumpInstructionLength,
+                            indirect_target)) {
+    InterceptionFailed();
+  }
+  *(u16*)from = 0x25FF;
+  *(u32*)(from + 2) = offset;
+}
+#endif
+
+static void WriteBranch(
+    uptr from, uptr indirect_target, uptr target) {
+#if SANITIZER_WINDOWS64
+  WriteIndirectJumpInstruction(from, indirect_target);
+  *(u64*)indirect_target = target;
+#else
+  (void)indirect_target;
+  WriteJumpInstruction(from, target);
+#endif
+}
+
+static void WriteDirectBranch(uptr from, uptr target) {
+#if SANITIZER_WINDOWS64
+  // Emit an indirect jump through immediately following bytes:
+  //   jmp [rip + kBranchLength]
+  //   .quad <target>
+  WriteBranch(from, from + kBranchLength, target);
+#else
+  WriteJumpInstruction(from, target);
+#endif
+}
+
+struct TrampolineMemoryRegion {
+  uptr content;
+  uptr allocated_size;
+  uptr max_size;
+};
+
+static const uptr kTrampolineScanLimitRange = 1 << 31;  // 2 gig
+static const int kMaxTrampolineRegion = 1024;
+static TrampolineMemoryRegion TrampolineRegions[kMaxTrampolineRegion];
+
+static void *AllocateTrampolineRegion(uptr image_address, size_t granularity) {
+#if SANITIZER_WINDOWS64
+  uptr address = image_address;
+  uptr scanned = 0;
+  while (scanned < kTrampolineScanLimitRange) {
+    MEMORY_BASIC_INFORMATION info;
+    if (!::VirtualQuery((void*)address, &info, sizeof(info)))
+      return nullptr;
+
+    // Check whether a region can be allocated at |address|.
+    if (info.State == MEM_FREE && info.RegionSize >= granularity) {
+      void *page = ::VirtualAlloc((void*)RoundUpTo(address, granularity),
+                                  granularity,
+                                  MEM_RESERVE | MEM_COMMIT,
+                                  PAGE_EXECUTE_READWRITE);
+      return page;
+    }
+
+    // Move to the next region.
+    address = (uptr)info.BaseAddress + info.RegionSize;
+    scanned += info.RegionSize;
+  }
+  return nullptr;
+#else
+  return ::VirtualAlloc(nullptr,
+                        granularity,
+                        MEM_RESERVE | MEM_COMMIT,
+                        PAGE_EXECUTE_READWRITE);
+#endif
+}
+
+// Used by unittests to release mapped memory space.
+void TestOnlyReleaseTrampolineRegions() {
+  for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) {
+    TrampolineMemoryRegion *current = &TrampolineRegions[bucket];
+    if (current->content == 0)
+      return;
+    ::VirtualFree((void*)current->content, 0, MEM_RELEASE);
+    current->content = 0;
+  }
+}
+
+static uptr AllocateMemoryForTrampoline(uptr image_address, size_t size) {
+  // Find a region within 2G with enough space to allocate |size| bytes.
+  TrampolineMemoryRegion *region = nullptr;
+  for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) {
+    TrampolineMemoryRegion* current = &TrampolineRegions[bucket];
+    if (current->content == 0) {
+      // No valid region found, allocate a new region.
+      size_t bucket_size = GetMmapGranularity();
+      void *content = AllocateTrampolineRegion(image_address, bucket_size);
+      if (content == nullptr)
+        return 0U;
+
+      current->content = (uptr)content;
+      current->allocated_size = 0;
+      current->max_size = bucket_size;
+      region = current;
+      break;
+    } else if (current->max_size - current->allocated_size > size) {
+#if SANITIZER_WINDOWS64
+        // In 64-bits, the memory space must be allocated within 2G boundary.
+        uptr next_address = current->content + current->allocated_size;
+        if (next_address < image_address ||
+            next_address - image_address >= 0x7FFF0000)
+          continue;
+#endif
+      // The space can be allocated in the current region.
+      region = current;
+      break;
+    }
+  }
+
+  // Failed to find a region.
+  if (region == nullptr)
+    return 0U;
+
+  // Allocate the space in the current region.
+  uptr allocated_space = region->content + region->allocated_size;
+  region->allocated_size += size;
+  WritePadding(allocated_space, size);
+
+  return allocated_space;
+}
+
+// Returns 0 on error.
+static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
+  switch (*(u64*)address) {
+    case 0x90909090909006EB:  // stub: jmp over 6 x nop.
+      return 8;
+  }
+
+  switch (*(u8*)address) {
+    case 0x90:  // 90 : nop
+      return 1;
+
+    case 0x50:  // push eax / rax
+    case 0x51:  // push ecx / rcx
+    case 0x52:  // push edx / rdx
+    case 0x53:  // push ebx / rbx
+    case 0x54:  // push esp / rsp
+    case 0x55:  // push ebp / rbp
+    case 0x56:  // push esi / rsi
+    case 0x57:  // push edi / rdi
+    case 0x5D:  // pop ebp / rbp
+      return 1;
+
+    case 0x6A:  // 6A XX = push XX
+      return 2;
+
+    case 0xb8:  // b8 XX XX XX XX : mov eax, XX XX XX XX
+    case 0xB9:  // b9 XX XX XX XX : mov ecx, XX XX XX XX
+      return 5;
+
+    // Cannot overwrite control-instruction. Return 0 to indicate failure.
+    case 0xE9:  // E9 XX XX XX XX : jmp <label>
+    case 0xE8:  // E8 XX XX XX XX : call <func>
+    case 0xC3:  // C3 : ret
+    case 0xEB:  // EB XX : jmp XX (short jump)
+    case 0x70:  // 7Y YY : jy XX (short conditional jump)
+    case 0x71:
+    case 0x72:
+    case 0x73:
+    case 0x74:
+    case 0x75:
+    case 0x76:
+    case 0x77:
+    case 0x78:
+    case 0x79:
+    case 0x7A:
+    case 0x7B:
+    case 0x7C:
+    case 0x7D:
+    case 0x7E:
+    case 0x7F:
+      return 0;
+  }
+
+  switch (*(u16*)(address)) {
+    case 0x018A:  // 8A 01 : mov al, byte ptr [ecx]
+    case 0xFF8B:  // 8B FF : mov edi, edi
+    case 0xEC8B:  // 8B EC : mov ebp, esp
+    case 0xc889:  // 89 C8 : mov eax, ecx
+    case 0xC18B:  // 8B C1 : mov eax, ecx
+    case 0xC033:  // 33 C0 : xor eax, eax
+    case 0xC933:  // 33 C9 : xor ecx, ecx
+    case 0xD233:  // 33 D2 : xor edx, edx
+      return 2;
+
+    // Cannot overwrite control-instruction. Return 0 to indicate failure.
+    case 0x25FF:  // FF 25 XX XX XX XX : jmp [XXXXXXXX]
+      return 0;
+  }
+
+  switch (0x00FFFFFF & *(u32*)address) {
+    case 0x24A48D:  // 8D A4 24 XX XX XX XX : lea esp, [esp + XX XX XX XX]
+      return 7;
+  }
+
+#if SANITIZER_WINDOWS64
+  switch (*(u8*)address) {
+    case 0xA1:  // A1 XX XX XX XX XX XX XX XX :
+                //   movabs eax, dword ptr ds:[XXXXXXXX]
+      return 9;
+  }
+
+  switch (*(u16*)address) {
+    case 0x5040:  // push rax
+    case 0x5140:  // push rcx
+    case 0x5240:  // push rdx
+    case 0x5340:  // push rbx
+    case 0x5440:  // push rsp
+    case 0x5540:  // push rbp
+    case 0x5640:  // push rsi
+    case 0x5740:  // push rdi
+    case 0x5441:  // push r12
+    case 0x5541:  // push r13
+    case 0x5641:  // push r14
+    case 0x5741:  // push r15
+    case 0x9066:  // Two-byte NOP
+      return 2;
+
+    case 0x058B:  // 8B 05 XX XX XX XX : mov eax, dword ptr [XX XX XX XX]
+      if (rel_offset)
+        *rel_offset = 2;
+      return 6;
+  }
+
+  switch (0x00FFFFFF & *(u32*)address) {
+    case 0xe58948:    // 48 8b c4 : mov rbp, rsp
+    case 0xc18b48:    // 48 8b c1 : mov rax, rcx
+    case 0xc48b48:    // 48 8b c4 : mov rax, rsp
+    case 0xd9f748:    // 48 f7 d9 : neg rcx
+    case 0xd12b48:    // 48 2b d1 : sub rdx, rcx
+    case 0x07c1f6:    // f6 c1 07 : test cl, 0x7
+    case 0xc98548:    // 48 85 C9 : test rcx, rcx
+    case 0xc0854d:    // 4d 85 c0 : test r8, r8
+    case 0xc2b60f:    // 0f b6 c2 : movzx eax, dl
+    case 0xc03345:    // 45 33 c0 : xor r8d, r8d
+    case 0xc93345:    // 45 33 c9 : xor r9d, r9d
+    case 0xdb3345:    // 45 33 DB : xor r11d, r11d
+    case 0xd98b4c:    // 4c 8b d9 : mov r11, rcx
+    case 0xd28b4c:    // 4c 8b d2 : mov r10, rdx
+    case 0xc98b4c:    // 4C 8B C9 : mov r9, rcx
+    case 0xc18b4c:    // 4C 8B C1 : mov r8, rcx
+    case 0xd2b60f:    // 0f b6 d2 : movzx edx, dl
+    case 0xca2b48:    // 48 2b ca : sub rcx, rdx
+    case 0x10b70f:    // 0f b7 10 : movzx edx, WORD PTR [rax]
+    case 0xc00b4d:    // 3d 0b c0 : or r8, r8
+    case 0xd18b48:    // 48 8b d1 : mov rdx, rcx
+    case 0xdc8b4c:    // 4c 8b dc : mov r11, rsp
+    case 0xd18b4c:    // 4c 8b d1 : mov r10, rcx
+    case 0xE0E483:    // 83 E4 E0 : and esp, 0xFFFFFFE0
+      return 3;
+
+    case 0xec8348:    // 48 83 ec XX : sub rsp, XX
+    case 0xf88349:    // 49 83 f8 XX : cmp r8, XX
+    case 0x588948:    // 48 89 58 XX : mov QWORD PTR[rax + XX], rbx
+      return 4;
+
+    case 0xec8148:    // 48 81 EC XX XX XX XX : sub rsp, XXXXXXXX
+      return 7;
+
+    case 0x058b48:    // 48 8b 05 XX XX XX XX :
+                      //   mov rax, QWORD PTR [rip + XXXXXXXX]
+    case 0x25ff48:    // 48 ff 25 XX XX XX XX :
+                      //   rex.W jmp QWORD PTR [rip + XXXXXXXX]
+
+      // Instructions having offset relative to 'rip' need offset adjustment.
+      if (rel_offset)
+        *rel_offset = 3;
+      return 7;
+
+    case 0x2444c7:    // C7 44 24 XX YY YY YY YY
+                      //   mov dword ptr [rsp + XX], YYYYYYYY
+      return 8;
+  }
+
+  switch (*(u32*)(address)) {
+    case 0x24448b48:  // 48 8b 44 24 XX : mov rax, QWORD ptr [rsp + XX]
+    case 0x246c8948:  // 48 89 6C 24 XX : mov QWORD ptr [rsp + XX], rbp
+    case 0x245c8948:  // 48 89 5c 24 XX : mov QWORD PTR [rsp + XX], rbx
+    case 0x24748948:  // 48 89 74 24 XX : mov QWORD PTR [rsp + XX], rsi
+    case 0x244C8948:  // 48 89 4C 24 XX : mov QWORD PTR [rsp + XX], rcx
+    case 0x24548948:  // 48 89 54 24 XX : mov QWORD PTR [rsp + XX], rdx
+    case 0x244c894c:  // 4c 89 4c 24 XX : mov QWORD PTR [rsp + XX], r9
+    case 0x2444894c:  // 4c 89 44 24 XX : mov QWORD PTR [rsp + XX], r8
+      return 5;
+    case 0x24648348:  // 48 83 64 24 XX : and QWORD PTR [rsp + XX], YY
+      return 6;
+  }
+
+#else
+
+  switch (*(u8*)address) {
+    case 0xA1:  // A1 XX XX XX XX :  mov eax, dword ptr ds:[XXXXXXXX]
+      return 5;
+  }
+  switch (*(u16*)address) {
+    case 0x458B:  // 8B 45 XX : mov eax, dword ptr [ebp + XX]
+    case 0x5D8B:  // 8B 5D XX : mov ebx, dword ptr [ebp + XX]
+    case 0x7D8B:  // 8B 7D XX : mov edi, dword ptr [ebp + XX]
+    case 0xEC83:  // 83 EC XX : sub esp, XX
+    case 0x75FF:  // FF 75 XX : push dword ptr [ebp + XX]
+      return 3;
+    case 0xC1F7:  // F7 C1 XX YY ZZ WW : test ecx, WWZZYYXX
+    case 0x25FF:  // FF 25 XX YY ZZ WW : jmp dword ptr ds:[WWZZYYXX]
+      return 6;
+    case 0x3D83:  // 83 3D XX YY ZZ WW TT : cmp TT, WWZZYYXX
+      return 7;
+    case 0x7D83:  // 83 7D XX YY : cmp dword ptr [ebp + XX], YY
+      return 4;
+  }
+
+  switch (0x00FFFFFF & *(u32*)address) {
+    case 0x24448A:  // 8A 44 24 XX : mov eal, dword ptr [esp + XX]
+    case 0x24448B:  // 8B 44 24 XX : mov eax, dword ptr [esp + XX]
+    case 0x244C8B:  // 8B 4C 24 XX : mov ecx, dword ptr [esp + XX]
+    case 0x24548B:  // 8B 54 24 XX : mov edx, dword ptr [esp + XX]
+    case 0x24748B:  // 8B 74 24 XX : mov esi, dword ptr [esp + XX]
+    case 0x247C8B:  // 8B 7C 24 XX : mov edi, dword ptr [esp + XX]
+      return 4;
+  }
+
+  switch (*(u32*)address) {
+    case 0x2444B60F:  // 0F B6 44 24 XX : movzx eax, byte ptr [esp + XX]
+      return 5;
+  }
+#endif
+
+  // Unknown instruction!
+  // FIXME: Unknown instruction failures might happen when we add a new
+  // interceptor or a new compiler version. In either case, they should result
+  // in visible and readable error messages. However, merely calling abort()
+  // leads to an infinite recursion in CheckFailed.
+  InterceptionFailed();
+  return 0;
+}
+
+// Returns 0 on error.
+static size_t RoundUpToInstrBoundary(size_t size, uptr address) {
+  size_t cursor = 0;
+  while (cursor < size) {
+    size_t instruction_size = GetInstructionSize(address + cursor);
+    if (!instruction_size)
+      return 0;
+    cursor += instruction_size;
+  }
+  return cursor;
+}
+
+static bool CopyInstructions(uptr to, uptr from, size_t size) {
+  size_t cursor = 0;
+  while (cursor != size) {
+    size_t rel_offset = 0;
+    size_t instruction_size = GetInstructionSize(from + cursor, &rel_offset);
+    _memcpy((void*)(to + cursor), (void*)(from + cursor),
+            (size_t)instruction_size);
+    if (rel_offset) {
+      uptr delta = to - from;
+      uptr relocated_offset = *(u32*)(to + cursor + rel_offset) - delta;
+#if SANITIZER_WINDOWS64
+      if (relocated_offset + 0x80000000U >= 0xFFFFFFFFU)
+        return false;
+#endif
+      *(u32*)(to + cursor + rel_offset) = relocated_offset;
+    }
+    cursor += instruction_size;
+  }
+  return true;
+}
+
+
+#if !SANITIZER_WINDOWS64
+bool OverrideFunctionWithDetour(
+    uptr old_func, uptr new_func, uptr *orig_old_func) {
+  const int kDetourHeaderLen = 5;
+  const u16 kDetourInstruction = 0xFF8B;
+
+  uptr header = (uptr)old_func - kDetourHeaderLen;
+  uptr patch_length = kDetourHeaderLen + kShortJumpInstructionLength;
+
+  // Validate that the function is hookable.
+  if (*(u16*)old_func != kDetourInstruction ||
+      !IsMemoryPadding(header, kDetourHeaderLen))
+    return false;
+
+  // Change memory protection to writable.
+  DWORD protection = 0;
+  if (!ChangeMemoryProtection(header, patch_length, &protection))
+    return false;
+
+  // Write a relative jump to the redirected function.
+  WriteJumpInstruction(header, new_func);
+
+  // Write the short jump to the function prefix.
+  WriteShortJumpInstruction(old_func, header);
+
+  // Restore previous memory protection.
+  if (!RestoreMemoryProtection(header, patch_length, protection))
+    return false;
+
+  if (orig_old_func)
+    *orig_old_func = old_func + kShortJumpInstructionLength;
+
+  return true;
+}
+#endif
+
+bool OverrideFunctionWithRedirectJump(
+    uptr old_func, uptr new_func, uptr *orig_old_func) {
+  // Check whether the first instruction is a relative jump.
+  if (*(u8*)old_func != 0xE9)
+    return false;
+
+  if (orig_old_func) {
+    uptr relative_offset = *(u32*)(old_func + 1);
+    uptr absolute_target = old_func + relative_offset + kJumpInstructionLength;
+    *orig_old_func = absolute_target;
+  }
+
+#if SANITIZER_WINDOWS64
+  // If needed, get memory space for a trampoline jump.
+  uptr trampoline = AllocateMemoryForTrampoline(old_func, kDirectBranchLength);
+  if (!trampoline)
+    return false;
+  WriteDirectBranch(trampoline, new_func);
+#endif
+
+  // Change memory protection to writable.
+  DWORD protection = 0;
+  if (!ChangeMemoryProtection(old_func, kJumpInstructionLength, &protection))
+    return false;
+
+  // Write a relative jump to the redirected function.
+  WriteJumpInstruction(old_func, FIRST_32_SECOND_64(new_func, trampoline));
+
+  // Restore previous memory protection.
+  if (!RestoreMemoryProtection(old_func, kJumpInstructionLength, protection))
+    return false;
+
+  return true;
+}
+
+bool OverrideFunctionWithHotPatch(
+    uptr old_func, uptr new_func, uptr *orig_old_func) {
+  const int kHotPatchHeaderLen = kBranchLength;
+
+  uptr header = (uptr)old_func - kHotPatchHeaderLen;
+  uptr patch_length = kHotPatchHeaderLen + kShortJumpInstructionLength;
+
+  // Validate that the function is hot patchable.
+  size_t instruction_size = GetInstructionSize(old_func);
+  if (instruction_size < kShortJumpInstructionLength ||
+      !FunctionHasPadding(old_func, kHotPatchHeaderLen))
+    return false;
+
+  if (orig_old_func) {
+    // Put the needed instructions into the trampoline bytes.
+    uptr trampoline_length = instruction_size + kDirectBranchLength;
+    uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length);
+    if (!trampoline)
+      return false;
+    if (!CopyInstructions(trampoline, old_func, instruction_size))
+      return false;
+    WriteDirectBranch(trampoline + instruction_size,
+                      old_func + instruction_size);
+    *orig_old_func = trampoline;
+  }
+
+  // If needed, get memory space for indirect address.
+  uptr indirect_address = 0;
+#if SANITIZER_WINDOWS64
+  indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength);
+  if (!indirect_address)
+    return false;
+#endif
+
+  // Change memory protection to writable.
+  DWORD protection = 0;
+  if (!ChangeMemoryProtection(header, patch_length, &protection))
+    return false;
+
+  // Write jumps to the redirected function.
+  WriteBranch(header, indirect_address, new_func);
+  WriteShortJumpInstruction(old_func, header);
+
+  // Restore previous memory protection.
+  if (!RestoreMemoryProtection(header, patch_length, protection))
+    return false;
+
+  return true;
+}
+
+bool OverrideFunctionWithTrampoline(
+    uptr old_func, uptr new_func, uptr *orig_old_func) {
+
+  size_t instructions_length = kBranchLength;
+  size_t padding_length = 0;
+  uptr indirect_address = 0;
+
+  if (orig_old_func) {
+    // Find out the number of bytes of the instructions we need to copy
+    // to the trampoline.
+    instructions_length = RoundUpToInstrBoundary(kBranchLength, old_func);
+    if (!instructions_length)
+      return false;
+
+    // Put the needed instructions into the trampoline bytes.
+    uptr trampoline_length = instructions_length + kDirectBranchLength;
+    uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length);
+    if (!trampoline)
+      return false;
+    if (!CopyInstructions(trampoline, old_func, instructions_length))
+      return false;
+    WriteDirectBranch(trampoline + instructions_length,
+                      old_func + instructions_length);
+    *orig_old_func = trampoline;
+  }
+
+#if SANITIZER_WINDOWS64
+  // Check if the targeted address can be encoded in the function padding.
+  // Otherwise, allocate it in the trampoline region.
+  if (IsMemoryPadding(old_func - kAddressLength, kAddressLength)) {
+    indirect_address = old_func - kAddressLength;
+    padding_length = kAddressLength;
+  } else {
+    indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength);
+    if (!indirect_address)
+      return false;
+  }
+#endif
+
+  // Change memory protection to writable.
+  uptr patch_address = old_func - padding_length;
+  uptr patch_length = instructions_length + padding_length;
+  DWORD protection = 0;
+  if (!ChangeMemoryProtection(patch_address, patch_length, &protection))
+    return false;
+
+  // Patch the original function.
+  WriteBranch(old_func, indirect_address, new_func);
+
+  // Restore previous memory protection.
+  if (!RestoreMemoryProtection(patch_address, patch_length, protection))
+    return false;
+
+  return true;
+}
+
+bool OverrideFunction(
+    uptr old_func, uptr new_func, uptr *orig_old_func) {
+#if !SANITIZER_WINDOWS64
+  if (OverrideFunctionWithDetour(old_func, new_func, orig_old_func))
+    return true;
+#endif
+  if (OverrideFunctionWithRedirectJump(old_func, new_func, orig_old_func))
+    return true;
+  if (OverrideFunctionWithHotPatch(old_func, new_func, orig_old_func))
+    return true;
+  if (OverrideFunctionWithTrampoline(old_func, new_func, orig_old_func))
+    return true;
+  return false;
+}
+
+static void **InterestingDLLsAvailable() {
+  static const char *InterestingDLLs[] = {
+      "kernel32.dll",
+      "msvcr100.dll",      // VS2010
+      "msvcr110.dll",      // VS2012
+      "msvcr120.dll",      // VS2013
+      "vcruntime140.dll",  // VS2015
+      "ucrtbase.dll",      // Universal CRT
+      // NTDLL should go last as it exports some functions that we should
+      // override in the CRT [presumably only used internally].
+      "ntdll.dll", NULL};
+  static void *result[ARRAY_SIZE(InterestingDLLs)] = { 0 };
+  if (!result[0]) {
+    for (size_t i = 0, j = 0; InterestingDLLs[i]; ++i) {
+      if (HMODULE h = GetModuleHandleA(InterestingDLLs[i]))
+        result[j++] = (void *)h;
+    }
+  }
+  return &result[0];
+}
+
+namespace {
+// Utility for reading loaded PE images.
+template <typename T> class RVAPtr {
+ public:
+  RVAPtr(void *module, uptr rva)
+      : ptr_(reinterpret_cast<T *>(reinterpret_cast<char *>(module) + rva)) {}
+  operator T *() { return ptr_; }
+  T *operator->() { return ptr_; }
+  T *operator++() { return ++ptr_; }
+
+ private:
+  T *ptr_;
+};
+} // namespace
+
+// Internal implementation of GetProcAddress. At least since Windows 8,
+// GetProcAddress appears to initialize DLLs before returning function pointers
+// into them. This is problematic for the sanitizers, because they typically
+// want to intercept malloc *before* MSVCRT initializes. Our internal
+// implementation walks the export list manually without doing initialization.
+uptr InternalGetProcAddress(void *module, const char *func_name) {
+  // Check that the module header is full and present.
+  RVAPtr<IMAGE_DOS_HEADER> dos_stub(module, 0);
+  RVAPtr<IMAGE_NT_HEADERS> headers(module, dos_stub->e_lfanew);
+  if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE ||  // "MZ"
+      headers->Signature != IMAGE_NT_SIGNATURE ||             // "PE\0\0"
+      headers->FileHeader.SizeOfOptionalHeader <
+          sizeof(IMAGE_OPTIONAL_HEADER)) {
+    return 0;
+  }
+
+  IMAGE_DATA_DIRECTORY *export_directory =
+      &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
+  if (export_directory->Size == 0)
+    return 0;
+  RVAPtr<IMAGE_EXPORT_DIRECTORY> exports(module,
+                                         export_directory->VirtualAddress);
+  RVAPtr<DWORD> functions(module, exports->AddressOfFunctions);
+  RVAPtr<DWORD> names(module, exports->AddressOfNames);
+  RVAPtr<WORD> ordinals(module, exports->AddressOfNameOrdinals);
+
+  for (DWORD i = 0; i < exports->NumberOfNames; i++) {
+    RVAPtr<char> name(module, names[i]);
+    if (!strcmp(func_name, name)) {
+      DWORD index = ordinals[i];
+      RVAPtr<char> func(module, functions[index]);
+
+      // Handle forwarded functions.
+      DWORD offset = functions[index];
+      if (offset >= export_directory->VirtualAddress &&
+          offset < export_directory->VirtualAddress + export_directory->Size) {
+        // An entry for a forwarded function is a string with the following
+        // format: "<module> . <function_name>" that is stored into the
+        // exported directory.
+        char function_name[256];
+        size_t funtion_name_length = _strlen(func);
+        if (funtion_name_length >= sizeof(function_name) - 1)
+          InterceptionFailed();
+
+        _memcpy(function_name, func, funtion_name_length);
+        function_name[funtion_name_length] = '\0';
+        char* separator = _strchr(function_name, '.');
+        if (!separator)
+          InterceptionFailed();
+        *separator = '\0';
+
+        void* redirected_module = GetModuleHandleA(function_name);
+        if (!redirected_module)
+          InterceptionFailed();
+        return InternalGetProcAddress(redirected_module, separator + 1);
+      }
+
+      return (uptr)(char *)func;
+    }
+  }
+
+  return 0;
+}
+
+bool OverrideFunction(
+    const char *func_name, uptr new_func, uptr *orig_old_func) {
+  bool hooked = false;
+  void **DLLs = InterestingDLLsAvailable();
+  for (size_t i = 0; DLLs[i]; ++i) {
+    uptr func_addr = InternalGetProcAddress(DLLs[i], func_name);
+    if (func_addr &&
+        OverrideFunction(func_addr, new_func, orig_old_func)) {
+      hooked = true;
+    }
+  }
+  return hooked;
+}
+
+bool OverrideImportedFunction(const char *module_to_patch,
+                              const char *imported_module,
+                              const char *function_name, uptr new_function,
+                              uptr *orig_old_func) {
+  HMODULE module = GetModuleHandleA(module_to_patch);
+  if (!module)
+    return false;
+
+  // Check that the module header is full and present.
+  RVAPtr<IMAGE_DOS_HEADER> dos_stub(module, 0);
+  RVAPtr<IMAGE_NT_HEADERS> headers(module, dos_stub->e_lfanew);
+  if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE ||  // "MZ"
+      headers->Signature != IMAGE_NT_SIGNATURE ||             // "PE\0\0"
+      headers->FileHeader.SizeOfOptionalHeader <
+          sizeof(IMAGE_OPTIONAL_HEADER)) {
+    return false;
+  }
+
+  IMAGE_DATA_DIRECTORY *import_directory =
+      &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT];
+
+  // Iterate the list of imported DLLs. FirstThunk will be null for the last
+  // entry.
+  RVAPtr<IMAGE_IMPORT_DESCRIPTOR> imports(module,
+                                          import_directory->VirtualAddress);
+  for (; imports->FirstThunk != 0; ++imports) {
+    RVAPtr<const char> modname(module, imports->Name);
+    if (_stricmp(&*modname, imported_module) == 0)
+      break;
+  }
+  if (imports->FirstThunk == 0)
+    return false;
+
+  // We have two parallel arrays: the import address table (IAT) and the table
+  // of names. They start out containing the same data, but the loader rewrites
+  // the IAT to hold imported addresses and leaves the name table in
+  // OriginalFirstThunk alone.
+  RVAPtr<IMAGE_THUNK_DATA> name_table(module, imports->OriginalFirstThunk);
+  RVAPtr<IMAGE_THUNK_DATA> iat(module, imports->FirstThunk);
+  for (; name_table->u1.Ordinal != 0; ++name_table, ++iat) {
+    if (!IMAGE_SNAP_BY_ORDINAL(name_table->u1.Ordinal)) {
+      RVAPtr<IMAGE_IMPORT_BY_NAME> import_by_name(
+          module, name_table->u1.ForwarderString);
+      const char *funcname = &import_by_name->Name[0];
+      if (strcmp(funcname, function_name) == 0)
+        break;
+    }
+  }
+  if (name_table->u1.Ordinal == 0)
+    return false;
+
+  // Now we have the correct IAT entry. Do the swap. We have to make the page
+  // read/write first.
+  if (orig_old_func)
+    *orig_old_func = iat->u1.AddressOfData;
+  DWORD old_prot, unused_prot;
+  if (!VirtualProtect(&iat->u1.AddressOfData, 4, PAGE_EXECUTE_READWRITE,
+                      &old_prot))
+    return false;
+  iat->u1.AddressOfData = new_function;
+  if (!VirtualProtect(&iat->u1.AddressOfData, 4, old_prot, &unused_prot))
+    return false;  // Not clear if this failure bothers us.
+  return true;
+}
+
+}  // namespace __interception
+
+#endif  // SANITIZER_MAC
diff --git a/lib/tsan/sanitizer_common/sanitizer_allocator_checks.cpp b/lib/tsan/sanitizer_common/sanitizer_allocator_checks.cpp
new file mode 100644
index 0000000000..9d67f679b5
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_allocator_checks.cpp
@@ -0,0 +1,22 @@
+//===-- sanitizer_allocator_checks.cpp --------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Various checks shared between ThreadSanitizer, MemorySanitizer, etc. memory
+// allocators.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_errno.h"
+
+namespace __sanitizer {
+
+void SetErrnoToENOMEM() {
+  errno = errno_ENOMEM;
+}
+
+} // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_allocator_report.cpp b/lib/tsan/sanitizer_common/sanitizer_allocator_report.cpp
new file mode 100644
index 0000000000..d74e08010d
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_allocator_report.cpp
@@ -0,0 +1,137 @@
+//===-- sanitizer_allocator_report.cpp --------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Shared allocator error reporting for ThreadSanitizer, MemorySanitizer, etc.
+///
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_allocator.h"
+#include "sanitizer_allocator_report.h"
+#include "sanitizer_common.h"
+#include "sanitizer_report_decorator.h"
+
+namespace __sanitizer {
+
+class ScopedAllocatorErrorReport {
+ public:
+  ScopedAllocatorErrorReport(const char *error_summary_,
+                             const StackTrace *stack_)
+      : error_summary(error_summary_),
+        stack(stack_) {
+    Printf("%s", d.Error());
+  }
+  ~ScopedAllocatorErrorReport() {
+    Printf("%s", d.Default());
+    stack->Print();
+    PrintHintAllocatorCannotReturnNull();
+    ReportErrorSummary(error_summary, stack);
+  }
+
+ private:
+  ScopedErrorReportLock lock;
+  const char *error_summary;
+  const StackTrace* const stack;
+  const SanitizerCommonDecorator d;
+};
+
+void NORETURN ReportCallocOverflow(uptr count, uptr size,
+                                   const StackTrace *stack) {
+  {
+    ScopedAllocatorErrorReport report("calloc-overflow", stack);
+    Report("ERROR: %s: calloc parameters overflow: count * size (%zd * %zd) "
+           "cannot be represented in type size_t\n", SanitizerToolName, count,
+           size);
+  }
+  Die();
+}
+
+void NORETURN ReportReallocArrayOverflow(uptr count, uptr size,
+                                         const StackTrace *stack) {
+  {
+    ScopedAllocatorErrorReport report("reallocarray-overflow", stack);
+    Report(
+        "ERROR: %s: reallocarray parameters overflow: count * size (%zd * %zd) "
+        "cannot be represented in type size_t\n",
+        SanitizerToolName, count, size);
+  }
+  Die();
+}
+
+void NORETURN ReportPvallocOverflow(uptr size, const StackTrace *stack) {
+  {
+    ScopedAllocatorErrorReport report("pvalloc-overflow", stack);
+    Report("ERROR: %s: pvalloc parameters overflow: size 0x%zx rounded up to "
+           "system page size 0x%zx cannot be represented in type size_t\n",
+           SanitizerToolName, size, GetPageSizeCached());
+  }
+  Die();
+}
+
+void NORETURN ReportInvalidAllocationAlignment(uptr alignment,
+                                               const StackTrace *stack) {
+  {
+    ScopedAllocatorErrorReport report("invalid-allocation-alignment", stack);
+    Report("ERROR: %s: invalid allocation alignment: %zd, alignment must be a "
+           "power of two\n", SanitizerToolName, alignment);
+  }
+  Die();
+}
+
+void NORETURN ReportInvalidAlignedAllocAlignment(uptr size, uptr alignment,
+                                                 const StackTrace *stack) {
+  {
+    ScopedAllocatorErrorReport report("invalid-aligned-alloc-alignment", stack);
+#if SANITIZER_POSIX
+    Report("ERROR: %s: invalid alignment requested in "
+           "aligned_alloc: %zd, alignment must be a power of two and the "
+           "requested size 0x%zx must be a multiple of alignment\n",
+           SanitizerToolName, alignment, size);
+#else
+    Report("ERROR: %s: invalid alignment requested in aligned_alloc: %zd, "
+           "the requested size 0x%zx must be a multiple of alignment\n",
+           SanitizerToolName, alignment, size);
+#endif
+  }
+  Die();
+}
+
+void NORETURN ReportInvalidPosixMemalignAlignment(uptr alignment,
+                                                  const StackTrace *stack) {
+  {
+    ScopedAllocatorErrorReport report("invalid-posix-memalign-alignment",
+                                      stack);
+    Report(
+        "ERROR: %s: invalid alignment requested in "
+        "posix_memalign: %zd, alignment must be a power of two and a "
+        "multiple of sizeof(void*) == %zd\n",
+        SanitizerToolName, alignment, sizeof(void *));
+  }
+  Die();
+}
+
+void NORETURN ReportAllocationSizeTooBig(uptr user_size, uptr max_size,
+                                         const StackTrace *stack) {
+  {
+    ScopedAllocatorErrorReport report("allocation-size-too-big", stack);
+    Report("ERROR: %s: requested allocation size 0x%zx exceeds maximum "
+           "supported size of 0x%zx\n", SanitizerToolName, user_size, max_size);
+  }
+  Die();
+}
+
+void NORETURN ReportOutOfMemory(uptr requested_size, const StackTrace *stack) {
+  {
+    ScopedAllocatorErrorReport report("out-of-memory", stack);
+    Report("ERROR: %s: allocator is out of memory trying to allocate 0x%zx "
+           "bytes\n", SanitizerToolName, requested_size);
+  }
+  Die();
+}
+
+}  // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_common_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_common_libcdep.cpp
new file mode 100644
index 0000000000..0c918ebb4a
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_common_libcdep.cpp
@@ -0,0 +1,149 @@
+//===-- sanitizer_common_libcdep.cpp --------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_allocator_interface.h"
+#include "sanitizer_common.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_procmaps.h"
+
+
+namespace __sanitizer {
+
+static void (*SoftRssLimitExceededCallback)(bool exceeded);
+void SetSoftRssLimitExceededCallback(void (*Callback)(bool exceeded)) {
+  CHECK_EQ(SoftRssLimitExceededCallback, nullptr);
+  SoftRssLimitExceededCallback = Callback;
+}
+
+#if (SANITIZER_LINUX || SANITIZER_NETBSD) && !SANITIZER_GO
+// Weak default implementation for when sanitizer_stackdepot is not linked in.
+SANITIZER_WEAK_ATTRIBUTE StackDepotStats *StackDepotGetStats() {
+  return nullptr;
+}
+
+void *BackgroundThread(void *arg) {
+  const uptr hard_rss_limit_mb = common_flags()->hard_rss_limit_mb;
+  const uptr soft_rss_limit_mb = common_flags()->soft_rss_limit_mb;
+  const bool heap_profile = common_flags()->heap_profile;
+  uptr prev_reported_rss = 0;
+  uptr prev_reported_stack_depot_size = 0;
+  bool reached_soft_rss_limit = false;
+  uptr rss_during_last_reported_profile = 0;
+  while (true) {
+    SleepForMillis(100);
+    const uptr current_rss_mb = GetRSS() >> 20;
+    if (Verbosity()) {
+      // If RSS has grown 10% since last time, print some information.
+      if (prev_reported_rss * 11 / 10 < current_rss_mb) {
+        Printf("%s: RSS: %zdMb\n", SanitizerToolName, current_rss_mb);
+        prev_reported_rss = current_rss_mb;
+      }
+      // If stack depot has grown 10% since last time, print it too.
+      StackDepotStats *stack_depot_stats = StackDepotGetStats();
+      if (stack_depot_stats) {
+        if (prev_reported_stack_depot_size * 11 / 10 <
+            stack_depot_stats->allocated) {
+          Printf("%s: StackDepot: %zd ids; %zdM allocated\n",
+                 SanitizerToolName,
+                 stack_depot_stats->n_uniq_ids,
+                 stack_depot_stats->allocated >> 20);
+          prev_reported_stack_depot_size = stack_depot_stats->allocated;
+        }
+      }
+    }
+    // Check RSS against the limit.
+    if (hard_rss_limit_mb && hard_rss_limit_mb < current_rss_mb) {
+      Report("%s: hard rss limit exhausted (%zdMb vs %zdMb)\n",
+             SanitizerToolName, hard_rss_limit_mb, current_rss_mb);
+      DumpProcessMap();
+      Die();
+    }
+    if (soft_rss_limit_mb) {
+      if (soft_rss_limit_mb < current_rss_mb && !reached_soft_rss_limit) {
+        reached_soft_rss_limit = true;
+        Report("%s: soft rss limit exhausted (%zdMb vs %zdMb)\n",
+               SanitizerToolName, soft_rss_limit_mb, current_rss_mb);
+        if (SoftRssLimitExceededCallback)
+          SoftRssLimitExceededCallback(true);
+      } else if (soft_rss_limit_mb >= current_rss_mb &&
+                 reached_soft_rss_limit) {
+        reached_soft_rss_limit = false;
+        if (SoftRssLimitExceededCallback)
+          SoftRssLimitExceededCallback(false);
+      }
+    }
+    if (heap_profile &&
+        current_rss_mb > rss_during_last_reported_profile * 1.1) {
+      Printf("\n\nHEAP PROFILE at RSS %zdMb\n", current_rss_mb);
+      __sanitizer_print_memory_profile(90, 20);
+      rss_during_last_reported_profile = current_rss_mb;
+    }
+  }
+}
+#endif
+
+void WriteToSyslog(const char *msg) {
+  InternalScopedString msg_copy(kErrorMessageBufferSize);
+  msg_copy.append("%s", msg);
+  char *p = msg_copy.data();
+  char *q;
+
+  // Print one line at a time.
+  // syslog, at least on Android, has an implicit message length limit.
+  while ((q = internal_strchr(p, '\n'))) {
+    *q = '\0';
+    WriteOneLineToSyslog(p);
+    p = q + 1;
+  }
+  // Print remaining characters, if there are any.
+  // Note that this will add an extra newline at the end.
+  // FIXME: buffer extra output. This would need a thread-local buffer, which
+  // on Android requires plugging into the tools (ex. ASan's) Thread class.
+  if (*p)
+    WriteOneLineToSyslog(p);
+}
+
+void MaybeStartBackgroudThread() {
+#if (SANITIZER_LINUX || SANITIZER_NETBSD) && \
+    !SANITIZER_GO  // Need to implement/test on other platforms.
+  // Start the background thread if one of the rss limits is given.
+  if (!common_flags()->hard_rss_limit_mb &&
+      !common_flags()->soft_rss_limit_mb &&
+      !common_flags()->heap_profile) return;
+  if (!&real_pthread_create) return;  // Can't spawn the thread anyway.
+  internal_start_thread(BackgroundThread, nullptr);
+#endif
+}
+
+static void (*sandboxing_callback)();
+void SetSandboxingCallback(void (*f)()) {
+  sandboxing_callback = f;
+}
+
+uptr ReservedAddressRange::InitAligned(uptr size, uptr align,
+                                       const char *name) {
+  CHECK(IsPowerOfTwo(align));
+  if (align <= GetPageSizeCached())
+    return Init(size, name);
+  uptr start = Init(size + align, name);
+  start += align - (start & (align - 1));
+  return start;
+}
+
+}  // namespace __sanitizer
+
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_sandbox_on_notify,
+                             __sanitizer_sandbox_arguments *args) {
+  __sanitizer::PlatformPrepareForSandboxing(args);
+  if (__sanitizer::sandboxing_callback)
+    __sanitizer::sandboxing_callback();
+}
diff --git a/lib/tsan/sanitizer_common/sanitizer_common_nolibc.cpp b/lib/tsan/sanitizer_common/sanitizer_common_nolibc.cpp
new file mode 100644
index 0000000000..3b278e017e
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_common_nolibc.cpp
@@ -0,0 +1,34 @@
+//===-- sanitizer_common_nolibc.cpp ---------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains stubs for libc function to facilitate optional use of
+// libc in no-libcdep sources.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#include "sanitizer_common.h"
+#include "sanitizer_libc.h"
+
+namespace __sanitizer {
+
+// The Windows implementations of these functions use the win32 API directly,
+// bypassing libc.
+#if !SANITIZER_WINDOWS
+#if SANITIZER_LINUX
+void LogMessageOnPrintf(const char *str) {}
+#endif
+void WriteToSyslog(const char *buffer) {}
+void Abort() { internal__exit(1); }
+void SleepForSeconds(int seconds) { internal_sleep(seconds); }
+#endif // !SANITIZER_WINDOWS
+
+#if !SANITIZER_WINDOWS && !SANITIZER_MAC
+void ListOfModules::init() {}
+#endif
+
+}  // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_linux_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_linux_libcdep.cpp
new file mode 100644
index 0000000000..4d17c9686e
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_linux_libcdep.cpp
@@ -0,0 +1,846 @@
+//===-- sanitizer_linux_libcdep.cpp ---------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries and implements linux-specific functions from
+// sanitizer_libc.h.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||                \
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
+
+#include "sanitizer_allocator_internal.h"
+#include "sanitizer_atomic.h"
+#include "sanitizer_common.h"
+#include "sanitizer_file.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_freebsd.h"
+#include "sanitizer_getauxval.h"
+#include "sanitizer_glibc_version.h"
+#include "sanitizer_linux.h"
+#include "sanitizer_placement_new.h"
+#include "sanitizer_procmaps.h"
+
+#include <dlfcn.h>  // for dlsym()
+#include <link.h>
+#include <pthread.h>
+#include <signal.h>
+#include <sys/resource.h>
+#include <syslog.h>
+
+#if !defined(ElfW)
+#define ElfW(type) Elf_##type
+#endif
+
+#if SANITIZER_FREEBSD
+#include <pthread_np.h>
+#include <osreldate.h>
+#include <sys/sysctl.h>
+#define pthread_getattr_np pthread_attr_get_np
+#endif
+
+#if SANITIZER_OPENBSD
+#include <pthread_np.h>
+#include <sys/sysctl.h>
+#endif
+
+#if SANITIZER_NETBSD
+#include <sys/sysctl.h>
+#include <sys/tls.h>
+#include <lwp.h>
+#endif
+
+#if SANITIZER_SOLARIS
+#include <stdlib.h>
+#include <thread.h>
+#endif
+
+#if SANITIZER_ANDROID
+#include <android/api-level.h>
+#if !defined(CPU_COUNT) && !defined(__aarch64__)
+#include <dirent.h>
+#include <fcntl.h>
+struct __sanitizer::linux_dirent {
+  long           d_ino;
+  off_t          d_off;
+  unsigned short d_reclen;
+  char           d_name[];
+};
+#endif
+#endif
+
+#if !SANITIZER_ANDROID
+#include <elf.h>
+#include <unistd.h>
+#endif
+
+namespace __sanitizer {
+
+SANITIZER_WEAK_ATTRIBUTE int
+real_sigaction(int signum, const void *act, void *oldact);
+
+int internal_sigaction(int signum, const void *act, void *oldact) {
+#if !SANITIZER_GO
+  if (&real_sigaction)
+    return real_sigaction(signum, act, oldact);
+#endif
+  return sigaction(signum, (const struct sigaction *)act,
+                   (struct sigaction *)oldact);
+}
+
+void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
+                                uptr *stack_bottom) {
+  CHECK(stack_top);
+  CHECK(stack_bottom);
+  if (at_initialization) {
+    // This is the main thread. Libpthread may not be initialized yet.
+    struct rlimit rl;
+    CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);
+
+    // Find the mapping that contains a stack variable.
+    MemoryMappingLayout proc_maps(/*cache_enabled*/true);
+    if (proc_maps.Error()) {
+      *stack_top = *stack_bottom = 0;
+      return;
+    }
+    MemoryMappedSegment segment;
+    uptr prev_end = 0;
+    while (proc_maps.Next(&segment)) {
+      if ((uptr)&rl < segment.end) break;
+      prev_end = segment.end;
+    }
+    CHECK((uptr)&rl >= segment.start && (uptr)&rl < segment.end);
+
+    // Get stacksize from rlimit, but clip it so that it does not overlap
+    // with other mappings.
+    uptr stacksize = rl.rlim_cur;
+    if (stacksize > segment.end - prev_end) stacksize = segment.end - prev_end;
+    // When running with unlimited stack size, we still want to set some limit.
+    // The unlimited stack size is caused by 'ulimit -s unlimited'.
+    // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
+    if (stacksize > kMaxThreadStackSize)
+      stacksize = kMaxThreadStackSize;
+    *stack_top = segment.end;
+    *stack_bottom = segment.end - stacksize;
+    return;
+  }
+  uptr stacksize = 0;
+  void *stackaddr = nullptr;
+#if SANITIZER_SOLARIS
+  stack_t ss;
+  CHECK_EQ(thr_stksegment(&ss), 0);
+  stacksize = ss.ss_size;
+  stackaddr = (char *)ss.ss_sp - stacksize;
+#elif SANITIZER_OPENBSD
+  stack_t sattr;
+  CHECK_EQ(pthread_stackseg_np(pthread_self(), &sattr), 0);
+  stackaddr = sattr.ss_sp;
+  stacksize = sattr.ss_size;
+#else  // !SANITIZER_SOLARIS
+  pthread_attr_t attr;
+  pthread_attr_init(&attr);
+  CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
+  my_pthread_attr_getstack(&attr, &stackaddr, &stacksize);
+  pthread_attr_destroy(&attr);
+#endif // SANITIZER_SOLARIS
+
+  *stack_top = (uptr)stackaddr + stacksize;
+  *stack_bottom = (uptr)stackaddr;
+}
+
+#if !SANITIZER_GO
+bool SetEnv(const char *name, const char *value) {
+  void *f = dlsym(RTLD_NEXT, "setenv");
+  if (!f)
+    return false;
+  typedef int(*setenv_ft)(const char *name, const char *value, int overwrite);
+  setenv_ft setenv_f;
+  CHECK_EQ(sizeof(setenv_f), sizeof(f));
+  internal_memcpy(&setenv_f, &f, sizeof(f));
+  return setenv_f(name, value, 1) == 0;
+}
+#endif
+
+__attribute__((unused)) static bool GetLibcVersion(int *major, int *minor,
+                                                   int *patch) {
+#ifdef _CS_GNU_LIBC_VERSION
+  char buf[64];
+  uptr len = confstr(_CS_GNU_LIBC_VERSION, buf, sizeof(buf));
+  if (len >= sizeof(buf))
+    return false;
+  buf[len] = 0;
+  static const char kGLibC[] = "glibc ";
+  if (internal_strncmp(buf, kGLibC, sizeof(kGLibC) - 1) != 0)
+    return false;
+  const char *p = buf + sizeof(kGLibC) - 1;
+  *major = internal_simple_strtoll(p, &p, 10);
+  *minor = (*p == '.') ? internal_simple_strtoll(p + 1, &p, 10) : 0;
+  *patch = (*p == '.') ? internal_simple_strtoll(p + 1, &p, 10) : 0;
+  return true;
+#else
+  return false;
+#endif
+}
+
+#if !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO &&               \
+    !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_SOLARIS
+static uptr g_tls_size;
+
+#ifdef __i386__
+# define CHECK_GET_TLS_STATIC_INFO_VERSION (!__GLIBC_PREREQ(2, 27))
+#else
+# define CHECK_GET_TLS_STATIC_INFO_VERSION 0
+#endif
+
+#if CHECK_GET_TLS_STATIC_INFO_VERSION
+# define DL_INTERNAL_FUNCTION __attribute__((regparm(3), stdcall))
+#else
+# define DL_INTERNAL_FUNCTION
+#endif
+
+namespace {
+struct GetTlsStaticInfoCall {
+  typedef void (*get_tls_func)(size_t*, size_t*);
+};
+struct GetTlsStaticInfoRegparmCall {
+  typedef void (*get_tls_func)(size_t*, size_t*) DL_INTERNAL_FUNCTION;
+};
+
+template <typename T>
+void CallGetTls(void* ptr, size_t* size, size_t* align) {
+  typename T::get_tls_func get_tls;
+  CHECK_EQ(sizeof(get_tls), sizeof(ptr));
+  internal_memcpy(&get_tls, &ptr, sizeof(ptr));
+  CHECK_NE(get_tls, 0);
+  get_tls(size, align);
+}
+
+bool CmpLibcVersion(int major, int minor, int patch) {
+  int ma;
+  int mi;
+  int pa;
+  if (!GetLibcVersion(&ma, &mi, &pa))
+    return false;
+  if (ma > major)
+    return true;
+  if (ma < major)
+    return false;
+  if (mi > minor)
+    return true;
+  if (mi < minor)
+    return false;
+  return pa >= patch;
+}
+
+}  // namespace
+
+void InitTlsSize() {
+  // all current supported platforms have 16 bytes stack alignment
+  const size_t kStackAlign = 16;
+  void *get_tls_static_info_ptr = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
+  size_t tls_size = 0;
+  size_t tls_align = 0;
+  // On i?86, _dl_get_tls_static_info used to be internal_function, i.e.
+  // __attribute__((regparm(3), stdcall)) before glibc 2.27 and is normal
+  // function in 2.27 and later.
+  if (CHECK_GET_TLS_STATIC_INFO_VERSION && !CmpLibcVersion(2, 27, 0))
+    CallGetTls<GetTlsStaticInfoRegparmCall>(get_tls_static_info_ptr,
+                                            &tls_size, &tls_align);
+  else
+    CallGetTls<GetTlsStaticInfoCall>(get_tls_static_info_ptr,
+                                     &tls_size, &tls_align);
+  if (tls_align < kStackAlign)
+    tls_align = kStackAlign;
+  g_tls_size = RoundUpTo(tls_size, tls_align);
+}
+#else
+void InitTlsSize() { }
+#endif  // !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO &&
+        // !SANITIZER_NETBSD && !SANITIZER_SOLARIS
+
+#if (defined(__x86_64__) || defined(__i386__) || defined(__mips__) ||          \
+     defined(__aarch64__) || defined(__powerpc64__) || defined(__s390__) ||    \
+     defined(__arm__)) &&                                                      \
+    SANITIZER_LINUX && !SANITIZER_ANDROID
+// sizeof(struct pthread) from glibc.
+static atomic_uintptr_t thread_descriptor_size;
+
+uptr ThreadDescriptorSize() {
+  uptr val = atomic_load_relaxed(&thread_descriptor_size);
+  if (val)
+    return val;
+#if defined(__x86_64__) || defined(__i386__) || defined(__arm__)
+  int major;
+  int minor;
+  int patch;
+  if (GetLibcVersion(&major, &minor, &patch) && major == 2) {
+    /* sizeof(struct pthread) values from various glibc versions.  */
+    if (SANITIZER_X32)
+      val = 1728; // Assume only one particular version for x32.
+    // For ARM sizeof(struct pthread) changed in Glibc 2.23.
+    else if (SANITIZER_ARM)
+      val = minor <= 22 ? 1120 : 1216;
+    else if (minor <= 3)
+      val = FIRST_32_SECOND_64(1104, 1696);
+    else if (minor == 4)
+      val = FIRST_32_SECOND_64(1120, 1728);
+    else if (minor == 5)
+      val = FIRST_32_SECOND_64(1136, 1728);
+    else if (minor <= 9)
+      val = FIRST_32_SECOND_64(1136, 1712);
+    else if (minor == 10)
+      val = FIRST_32_SECOND_64(1168, 1776);
+    else if (minor == 11 || (minor == 12 && patch == 1))
+      val = FIRST_32_SECOND_64(1168, 2288);
+    else if (minor <= 14)
+      val = FIRST_32_SECOND_64(1168, 2304);
+    else
+      val = FIRST_32_SECOND_64(1216, 2304);
+  }
+#elif defined(__mips__)
+  // TODO(sagarthakur): add more values as per different glibc versions.
+  val = FIRST_32_SECOND_64(1152, 1776);
+#elif defined(__aarch64__)
+  // The sizeof (struct pthread) is the same from GLIBC 2.17 to 2.22.
+  val = 1776;
+#elif defined(__powerpc64__)
+  val = 1776; // from glibc.ppc64le 2.20-8.fc21
+#elif defined(__s390__)
+  val = FIRST_32_SECOND_64(1152, 1776); // valid for glibc 2.22
+#endif
+  if (val)
+    atomic_store_relaxed(&thread_descriptor_size, val);
+  return val;
+}
+
+// The offset at which pointer to self is located in the thread descriptor.
+const uptr kThreadSelfOffset = FIRST_32_SECOND_64(8, 16);
+
+uptr ThreadSelfOffset() {
+  return kThreadSelfOffset;
+}
+
+#if defined(__mips__) || defined(__powerpc64__)
+// TlsPreTcbSize includes size of struct pthread_descr and size of tcb
+// head structure. It lies before the static tls blocks.
+static uptr TlsPreTcbSize() {
+# if defined(__mips__)
+  const uptr kTcbHead = 16; // sizeof (tcbhead_t)
+# elif defined(__powerpc64__)
+  const uptr kTcbHead = 88; // sizeof (tcbhead_t)
+# endif
+  const uptr kTlsAlign = 16;
+  const uptr kTlsPreTcbSize =
+      RoundUpTo(ThreadDescriptorSize() + kTcbHead, kTlsAlign);
+  return kTlsPreTcbSize;
+}
+#endif
+
+uptr ThreadSelf() {
+  uptr descr_addr;
+# if defined(__i386__)
+  asm("mov %%gs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
+# elif defined(__x86_64__)
+  asm("mov %%fs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
+# elif defined(__mips__)
+  // MIPS uses TLS variant I. The thread pointer (in hardware register $29)
+  // points to the end of the TCB + 0x7000. The pthread_descr structure is
+  // immediately in front of the TCB. TlsPreTcbSize() includes the size of the
+  // TCB and the size of pthread_descr.
+  const uptr kTlsTcbOffset = 0x7000;
+  uptr thread_pointer;
+  asm volatile(".set push;\
+                .set mips64r2;\
+                rdhwr %0,$29;\
+                .set pop" : "=r" (thread_pointer));
+  descr_addr = thread_pointer - kTlsTcbOffset - TlsPreTcbSize();
+# elif defined(__aarch64__) || defined(__arm__)
+  descr_addr = reinterpret_cast<uptr>(__builtin_thread_pointer()) -
+                                      ThreadDescriptorSize();
+# elif defined(__s390__)
+  descr_addr = reinterpret_cast<uptr>(__builtin_thread_pointer());
+# elif defined(__powerpc64__)
+  // PPC64LE uses TLS variant I. The thread pointer (in GPR 13)
+  // points to the end of the TCB + 0x7000. The pthread_descr structure is
+  // immediately in front of the TCB. TlsPreTcbSize() includes the size of the
+  // TCB and the size of pthread_descr.
+  const uptr kTlsTcbOffset = 0x7000;
+  uptr thread_pointer;
+  asm("addi %0,13,%1" : "=r"(thread_pointer) : "I"(-kTlsTcbOffset));
+  descr_addr = thread_pointer - TlsPreTcbSize();
+# else
+#  error "unsupported CPU arch"
+# endif
+  return descr_addr;
+}
+#endif  // (x86_64 || i386 || MIPS) && SANITIZER_LINUX
+
+#if SANITIZER_FREEBSD
+static void **ThreadSelfSegbase() {
+  void **segbase = 0;
+# if defined(__i386__)
+  // sysarch(I386_GET_GSBASE, segbase);
+  __asm __volatile("mov %%gs:0, %0" : "=r" (segbase));
+# elif defined(__x86_64__)
+  // sysarch(AMD64_GET_FSBASE, segbase);
+  __asm __volatile("movq %%fs:0, %0" : "=r" (segbase));
+# else
+#  error "unsupported CPU arch"
+# endif
+  return segbase;
+}
+
+uptr ThreadSelf() {
+  return (uptr)ThreadSelfSegbase()[2];
+}
+#endif  // SANITIZER_FREEBSD
+
+#if SANITIZER_NETBSD
+static struct tls_tcb * ThreadSelfTlsTcb() {
+  return (struct tls_tcb *)_lwp_getprivate();
+}
+
+uptr ThreadSelf() {
+  return (uptr)ThreadSelfTlsTcb()->tcb_pthread;
+}
+
+int GetSizeFromHdr(struct dl_phdr_info *info, size_t size, void *data) {
+  const Elf_Phdr *hdr = info->dlpi_phdr;
+  const Elf_Phdr *last_hdr = hdr + info->dlpi_phnum;
+
+  for (; hdr != last_hdr; ++hdr) {
+    if (hdr->p_type == PT_TLS && info->dlpi_tls_modid == 1) {
+      *(uptr*)data = hdr->p_memsz;
+      break;
+    }
+  }
+  return 0;
+}
+#endif  // SANITIZER_NETBSD
+
+#if !SANITIZER_GO
+static void GetTls(uptr *addr, uptr *size) {
+#if SANITIZER_LINUX && !SANITIZER_ANDROID
+# if defined(__x86_64__) || defined(__i386__) || defined(__s390__)
+  *addr = ThreadSelf();
+  *size = GetTlsSize();
+  *addr -= *size;
+  *addr += ThreadDescriptorSize();
+# elif defined(__mips__) || defined(__aarch64__) || defined(__powerpc64__) \
+    || defined(__arm__)
+  *addr = ThreadSelf();
+  *size = GetTlsSize();
+# else
+  *addr = 0;
+  *size = 0;
+# endif
+#elif SANITIZER_FREEBSD
+  void** segbase = ThreadSelfSegbase();
+  *addr = 0;
+  *size = 0;
+  if (segbase != 0) {
+    // tcbalign = 16
+    // tls_size = round(tls_static_space, tcbalign);
+    // dtv = segbase[1];
+    // dtv[2] = segbase - tls_static_space;
+    void **dtv = (void**) segbase[1];
+    *addr = (uptr) dtv[2];
+    *size = (*addr == 0) ? 0 : ((uptr) segbase[0] - (uptr) dtv[2]);
+  }
+#elif SANITIZER_NETBSD
+  struct tls_tcb * const tcb = ThreadSelfTlsTcb();
+  *addr = 0;
+  *size = 0;
+  if (tcb != 0) {
+    // Find size (p_memsz) of dlpi_tls_modid 1 (TLS block of the main program).
+    // ld.elf_so hardcodes the index 1.
+    dl_iterate_phdr(GetSizeFromHdr, size);
+
+    if (*size != 0) {
+      // The block has been found and tcb_dtv[1] contains the base address
+      *addr = (uptr)tcb->tcb_dtv[1];
+    }
+  }
+#elif SANITIZER_OPENBSD
+  *addr = 0;
+  *size = 0;
+#elif SANITIZER_ANDROID
+  *addr = 0;
+  *size = 0;
+#elif SANITIZER_SOLARIS
+  // FIXME
+  *addr = 0;
+  *size = 0;
+#else
+# error "Unknown OS"
+#endif
+}
+#endif
+
+#if !SANITIZER_GO
+uptr GetTlsSize() {
+#if SANITIZER_FREEBSD || SANITIZER_ANDROID || SANITIZER_NETBSD ||              \
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
+  uptr addr, size;
+  GetTls(&addr, &size);
+  return size;
+#elif defined(__mips__) || defined(__powerpc64__)
+  return RoundUpTo(g_tls_size + TlsPreTcbSize(), 16);
+#else
+  return g_tls_size;
+#endif
+}
+#endif
+
+void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
+                          uptr *tls_addr, uptr *tls_size) {
+#if SANITIZER_GO
+  // Stub implementation for Go.
+  *stk_addr = *stk_size = *tls_addr = *tls_size = 0;
+#else
+  GetTls(tls_addr, tls_size);
+
+  uptr stack_top, stack_bottom;
+  GetThreadStackTopAndBottom(main, &stack_top, &stack_bottom);
+  *stk_addr = stack_bottom;
+  *stk_size = stack_top - stack_bottom;
+
+  if (!main) {
+    // If stack and tls intersect, make them non-intersecting.
+    if (*tls_addr > *stk_addr && *tls_addr < *stk_addr + *stk_size) {
+      CHECK_GT(*tls_addr + *tls_size, *stk_addr);
+      CHECK_LE(*tls_addr + *tls_size, *stk_addr + *stk_size);
+      *stk_size -= *tls_size;
+      *tls_addr = *stk_addr + *stk_size;
+    }
+  }
+#endif
+}
+
+#if !SANITIZER_FREEBSD && !SANITIZER_OPENBSD
+typedef ElfW(Phdr) Elf_Phdr;
+#elif SANITIZER_WORDSIZE == 32 && __FreeBSD_version <= 902001 // v9.2
+#define Elf_Phdr XElf32_Phdr
+#define dl_phdr_info xdl_phdr_info
+#define dl_iterate_phdr(c, b) xdl_iterate_phdr((c), (b))
+#endif // !SANITIZER_FREEBSD && !SANITIZER_OPENBSD
+
+struct DlIteratePhdrData {
+  InternalMmapVectorNoCtor<LoadedModule> *modules;
+  bool first;
+};
+
+static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
+  DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
+  InternalScopedString module_name(kMaxPathLength);
+  if (data->first) {
+    data->first = false;
+    // First module is the binary itself.
+    ReadBinaryNameCached(module_name.data(), module_name.size());
+  } else if (info->dlpi_name) {
+    module_name.append("%s", info->dlpi_name);
+  }
+  if (module_name[0] == '\0')
+    return 0;
+  LoadedModule cur_module;
+  cur_module.set(module_name.data(), info->dlpi_addr);
+  for (int i = 0; i < (int)info->dlpi_phnum; i++) {
+    const Elf_Phdr *phdr = &info->dlpi_phdr[i];
+    if (phdr->p_type == PT_LOAD) {
+      uptr cur_beg = info->dlpi_addr + phdr->p_vaddr;
+      uptr cur_end = cur_beg + phdr->p_memsz;
+      bool executable = phdr->p_flags & PF_X;
+      bool writable = phdr->p_flags & PF_W;
+      cur_module.addAddressRange(cur_beg, cur_end, executable,
+                                 writable);
+    }
+  }
+  data->modules->push_back(cur_module);
+  return 0;
+}
+
+#if SANITIZER_ANDROID && __ANDROID_API__ < 21
+extern "C" __attribute__((weak)) int dl_iterate_phdr(
+    int (*)(struct dl_phdr_info *, size_t, void *), void *);
+#endif
+
+static bool requiresProcmaps() {
+#if SANITIZER_ANDROID && __ANDROID_API__ <= 22
+  // Fall back to /proc/maps if dl_iterate_phdr is unavailable or broken.
+  // The runtime check allows the same library to work with
+  // both K and L (and future) Android releases.
+  return AndroidGetApiLevel() <= ANDROID_LOLLIPOP_MR1;
+#else
+  return false;
+#endif
+}
+
+static void procmapsInit(InternalMmapVectorNoCtor<LoadedModule> *modules) {
+  MemoryMappingLayout memory_mapping(/*cache_enabled*/true);
+  memory_mapping.DumpListOfModules(modules);
+}
+
+void ListOfModules::init() {
+  clearOrInit();
+  if (requiresProcmaps()) {
+    procmapsInit(&modules_);
+  } else {
+    DlIteratePhdrData data = {&modules_, true};
+    dl_iterate_phdr(dl_iterate_phdr_cb, &data);
+  }
+}
+
+// When a custom loader is used, dl_iterate_phdr may not contain the full
+// list of modules. Allow callers to fall back to using procmaps.
+void ListOfModules::fallbackInit() {
+  if (!requiresProcmaps()) {
+    clearOrInit();
+    procmapsInit(&modules_);
+  } else {
+    clear();
+  }
+}
+
+// getrusage does not give us the current RSS, only the max RSS.
+// Still, this is better than nothing if /proc/self/statm is not available
+// for some reason, e.g. due to a sandbox.
+static uptr GetRSSFromGetrusage() {
+  struct rusage usage;
+  if (getrusage(RUSAGE_SELF, &usage))  // Failed, probably due to a sandbox.
+    return 0;
+  return usage.ru_maxrss << 10;  // ru_maxrss is in Kb.
+}
+
+uptr GetRSS() {
+  if (!common_flags()->can_use_proc_maps_statm)
+    return GetRSSFromGetrusage();
+  fd_t fd = OpenFile("/proc/self/statm", RdOnly);
+  if (fd == kInvalidFd)
+    return GetRSSFromGetrusage();
+  char buf[64];
+  uptr len = internal_read(fd, buf, sizeof(buf) - 1);
+  internal_close(fd);
+  if ((sptr)len <= 0)
+    return 0;
+  buf[len] = 0;
+  // The format of the file is:
+  // 1084 89 69 11 0 79 0
+  // We need the second number which is RSS in pages.
+  char *pos = buf;
+  // Skip the first number.
+  while (*pos >= '0' && *pos <= '9')
+    pos++;
+  // Skip whitespaces.
+  while (!(*pos >= '0' && *pos <= '9') && *pos != 0)
+    pos++;
+  // Read the number.
+  uptr rss = 0;
+  while (*pos >= '0' && *pos <= '9')
+    rss = rss * 10 + *pos++ - '0';
+  return rss * GetPageSizeCached();
+}
+
+// sysconf(_SC_NPROCESSORS_{CONF,ONLN}) cannot be used on most platforms as
+// they allocate memory.
+u32 GetNumberOfCPUs() {
+#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD
+  u32 ncpu;
+  int req[2];
+  uptr len = sizeof(ncpu);
+  req[0] = CTL_HW;
+  req[1] = HW_NCPU;
+  CHECK_EQ(internal_sysctl(req, 2, &ncpu, &len, NULL, 0), 0);
+  return ncpu;
+#elif SANITIZER_ANDROID && !defined(CPU_COUNT) && !defined(__aarch64__)
+  // Fall back to /sys/devices/system/cpu on Android when cpu_set_t doesn't
+  // exist in sched.h. That is the case for toolchains generated with older
+  // NDKs.
+  // This code doesn't work on AArch64 because internal_getdents makes use of
+  // the 64bit getdents syscall, but cpu_set_t seems to always exist on AArch64.
+  uptr fd = internal_open("/sys/devices/system/cpu", O_RDONLY | O_DIRECTORY);
+  if (internal_iserror(fd))
+    return 0;
+  InternalMmapVector<u8> buffer(4096);
+  uptr bytes_read = buffer.size();
+  uptr n_cpus = 0;
+  u8 *d_type;
+  struct linux_dirent *entry = (struct linux_dirent *)&buffer[bytes_read];
+  while (true) {
+    if ((u8 *)entry >= &buffer[bytes_read]) {
+      bytes_read = internal_getdents(fd, (struct linux_dirent *)buffer.data(),
+                                     buffer.size());
+      if (internal_iserror(bytes_read) || !bytes_read)
+        break;
+      entry = (struct linux_dirent *)buffer.data();
+    }
+    d_type = (u8 *)entry + entry->d_reclen - 1;
+    if (d_type >= &buffer[bytes_read] ||
+        (u8 *)&entry->d_name[3] >= &buffer[bytes_read])
+      break;
+    if (entry->d_ino != 0 && *d_type == DT_DIR) {
+      if (entry->d_name[0] == 'c' && entry->d_name[1] == 'p' &&
+          entry->d_name[2] == 'u' &&
+          entry->d_name[3] >= '0' && entry->d_name[3] <= '9')
+        n_cpus++;
+    }
+    entry = (struct linux_dirent *)(((u8 *)entry) + entry->d_reclen);
+  }
+  internal_close(fd);
+  return n_cpus;
+#elif SANITIZER_SOLARIS
+  return sysconf(_SC_NPROCESSORS_ONLN);
+#else
+  cpu_set_t CPUs;
+  CHECK_EQ(sched_getaffinity(0, sizeof(cpu_set_t), &CPUs), 0);
+  return CPU_COUNT(&CPUs);
+#endif
+}
+
+#if SANITIZER_LINUX
+
+# if SANITIZER_ANDROID
+static atomic_uint8_t android_log_initialized;
+
+void AndroidLogInit() {
+  openlog(GetProcessName(), 0, LOG_USER);
+  atomic_store(&android_log_initialized, 1, memory_order_release);
+}
+
+static bool ShouldLogAfterPrintf() {
+  return atomic_load(&android_log_initialized, memory_order_acquire);
+}
+
+extern "C" SANITIZER_WEAK_ATTRIBUTE
+int async_safe_write_log(int pri, const char* tag, const char* msg);
+extern "C" SANITIZER_WEAK_ATTRIBUTE
+int __android_log_write(int prio, const char* tag, const char* msg);
+
+// ANDROID_LOG_INFO is 4, but can't be resolved at runtime.
+#define SANITIZER_ANDROID_LOG_INFO 4
+
+// async_safe_write_log is a new public version of __libc_write_log that is
+// used behind syslog. It is preferable to syslog as it will not do any dynamic
+// memory allocation or formatting.
+// If the function is not available, syslog is preferred for L+ (it was broken
+// pre-L) as __android_log_write triggers a racey behavior with the strncpy
+// interceptor. Fallback to __android_log_write pre-L.
+void WriteOneLineToSyslog(const char *s) {
+  if (&async_safe_write_log) {
+    async_safe_write_log(SANITIZER_ANDROID_LOG_INFO, GetProcessName(), s);
+  } else if (AndroidGetApiLevel() > ANDROID_KITKAT) {
+    syslog(LOG_INFO, "%s", s);
+  } else {
+    CHECK(&__android_log_write);
+    __android_log_write(SANITIZER_ANDROID_LOG_INFO, nullptr, s);
+  }
+}
+
+extern "C" SANITIZER_WEAK_ATTRIBUTE
+void android_set_abort_message(const char *);
+
+void SetAbortMessage(const char *str) {
+  if (&android_set_abort_message)
+    android_set_abort_message(str);
+}
+# else
+void AndroidLogInit() {}
+
+static bool ShouldLogAfterPrintf() { return true; }
+
+void WriteOneLineToSyslog(const char *s) { syslog(LOG_INFO, "%s", s); }
+
+void SetAbortMessage(const char *str) {}
+# endif  // SANITIZER_ANDROID
+
+void LogMessageOnPrintf(const char *str) {
+  if (common_flags()->log_to_syslog && ShouldLogAfterPrintf())
+    WriteToSyslog(str);
+}
+
+#endif  // SANITIZER_LINUX
+
+#if SANITIZER_LINUX && !SANITIZER_GO
+// glibc crashes when using clock_gettime from a preinit_array function as the
+// vDSO function pointers haven't been initialized yet. __progname is
+// initialized after the vDSO function pointers, so if it exists, is not null
+// and is not empty, we can use clock_gettime.
+extern "C" SANITIZER_WEAK_ATTRIBUTE char *__progname;
+INLINE bool CanUseVDSO() {
+  // Bionic is safe, it checks for the vDSO function pointers to be initialized.
+  if (SANITIZER_ANDROID)
+    return true;
+  if (&__progname && __progname && *__progname)
+    return true;
+  return false;
+}
+
+// MonotonicNanoTime is a timing function that can leverage the vDSO by calling
+// clock_gettime. real_clock_gettime only exists if clock_gettime is
+// intercepted, so define it weakly and use it if available.
+extern "C" SANITIZER_WEAK_ATTRIBUTE
+int real_clock_gettime(u32 clk_id, void *tp);
+u64 MonotonicNanoTime() {
+  timespec ts;
+  if (CanUseVDSO()) {
+    if (&real_clock_gettime)
+      real_clock_gettime(CLOCK_MONOTONIC, &ts);
+    else
+      clock_gettime(CLOCK_MONOTONIC, &ts);
+  } else {
+    internal_clock_gettime(CLOCK_MONOTONIC, &ts);
+  }
+  return (u64)ts.tv_sec * (1000ULL * 1000 * 1000) + ts.tv_nsec;
+}
+#else
+// Non-Linux & Go always use the syscall.
+u64 MonotonicNanoTime() {
+  timespec ts;
+  internal_clock_gettime(CLOCK_MONOTONIC, &ts);
+  return (u64)ts.tv_sec * (1000ULL * 1000 * 1000) + ts.tv_nsec;
+}
+#endif  // SANITIZER_LINUX && !SANITIZER_GO
+
+#if !SANITIZER_OPENBSD
+void ReExec() {
+  const char *pathname = "/proc/self/exe";
+
+#if SANITIZER_NETBSD
+  static const int name[] = {
+      CTL_KERN,
+      KERN_PROC_ARGS,
+      -1,
+      KERN_PROC_PATHNAME,
+  };
+  char path[400];
+  uptr len;
+
+  len = sizeof(path);
+  if (internal_sysctl(name, ARRAY_SIZE(name), path, &len, NULL, 0) != -1)
+    pathname = path;
+#elif SANITIZER_SOLARIS
+  pathname = getexecname();
+  CHECK_NE(pathname, NULL);
+#elif SANITIZER_USE_GETAUXVAL
+  // Calling execve with /proc/self/exe sets that as $EXEC_ORIGIN. Binaries that
+  // rely on that will fail to load shared libraries. Query AT_EXECFN instead.
+  pathname = reinterpret_cast<const char *>(getauxval(AT_EXECFN));
+#endif
+
+  uptr rv = internal_execve(pathname, GetArgv(), GetEnviron());
+  int rverrno;
+  CHECK_EQ(internal_iserror(rv, &rverrno), true);
+  Printf("execve failed, errno %d\n", rverrno);
+  Die();
+}
+#endif  // !SANITIZER_OPENBSD
+
+} // namespace __sanitizer
+
+#endif
diff --git a/lib/tsan/sanitizer_common/sanitizer_mac_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_mac_libcdep.cpp
new file mode 100644
index 0000000000..ac7e328946
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_mac_libcdep.cpp
@@ -0,0 +1,29 @@
+//===-- sanitizer_mac_libcdep.cpp -----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between various sanitizers' runtime libraries and
+// implements OSX-specific functions.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_MAC
+#include "sanitizer_mac.h"
+
+#include <sys/mman.h>
+
+namespace __sanitizer {
+
+void RestrictMemoryToMaxAddress(uptr max_address) {
+  uptr size_to_mmap = GetMaxUserVirtualAddress() + 1 - max_address;
+  void *res = MmapFixedNoAccess(max_address, size_to_mmap, "high gap");
+  CHECK(res != MAP_FAILED);
+}
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_MAC
diff --git a/lib/tsan/sanitizer_common/sanitizer_posix_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_posix_libcdep.cpp
new file mode 100644
index 0000000000..f920172c06
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_posix_libcdep.cpp
@@ -0,0 +1,509 @@
+//===-- sanitizer_posix_libcdep.cpp ---------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries and implements libc-dependent POSIX-specific functions
+// from sanitizer_libc.h.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#if SANITIZER_POSIX
+
+#include "sanitizer_common.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_platform_limits_netbsd.h"
+#include "sanitizer_platform_limits_openbsd.h"
+#include "sanitizer_platform_limits_posix.h"
+#include "sanitizer_platform_limits_solaris.h"
+#include "sanitizer_posix.h"
+#include "sanitizer_procmaps.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#if SANITIZER_FREEBSD
+// The MAP_NORESERVE define has been removed in FreeBSD 11.x, and even before
+// that, it was never implemented.  So just define it to zero.
+#undef MAP_NORESERVE
+#define MAP_NORESERVE 0
+#endif
+
+typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
+
+namespace __sanitizer {
+
+u32 GetUid() {
+  return getuid();
+}
+
+uptr GetThreadSelf() {
+  return (uptr)pthread_self();
+}
+
+void ReleaseMemoryPagesToOS(uptr beg, uptr end) {
+  uptr page_size = GetPageSizeCached();
+  uptr beg_aligned = RoundUpTo(beg, page_size);
+  uptr end_aligned = RoundDownTo(end, page_size);
+  if (beg_aligned < end_aligned)
+    // In the default Solaris compilation environment, madvise() is declared
+    // to take a caddr_t arg; casting it to void * results in an invalid
+    // conversion error, so use char * instead.
+    madvise((char *)beg_aligned, end_aligned - beg_aligned,
+            SANITIZER_MADVISE_DONTNEED);
+}
+
+void SetShadowRegionHugePageMode(uptr addr, uptr size) {
+#ifdef MADV_NOHUGEPAGE  // May not be defined on old systems.
+  if (common_flags()->no_huge_pages_for_shadow)
+    madvise((char *)addr, size, MADV_NOHUGEPAGE);
+  else
+    madvise((char *)addr, size, MADV_HUGEPAGE);
+#endif  // MADV_NOHUGEPAGE
+}
+
+bool DontDumpShadowMemory(uptr addr, uptr length) {
+#if defined(MADV_DONTDUMP)
+  return madvise((char *)addr, length, MADV_DONTDUMP) == 0;
+#elif defined(MADV_NOCORE)
+  return madvise((char *)addr, length, MADV_NOCORE) == 0;
+#else
+  return true;
+#endif  // MADV_DONTDUMP
+}
+
+static rlim_t getlim(int res) {
+  rlimit rlim;
+  CHECK_EQ(0, getrlimit(res, &rlim));
+  return rlim.rlim_cur;
+}
+
+static void setlim(int res, rlim_t lim) {
+  struct rlimit rlim;
+  if (getrlimit(res, const_cast<struct rlimit *>(&rlim))) {
+    Report("ERROR: %s getrlimit() failed %d\n", SanitizerToolName, errno);
+    Die();
+  }
+  rlim.rlim_cur = lim;
+  if (setrlimit(res, const_cast<struct rlimit *>(&rlim))) {
+    Report("ERROR: %s setrlimit() failed %d\n", SanitizerToolName, errno);
+    Die();
+  }
+}
+
+void DisableCoreDumperIfNecessary() {
+  if (common_flags()->disable_coredump) {
+    setlim(RLIMIT_CORE, 0);
+  }
+}
+
+bool StackSizeIsUnlimited() {
+  rlim_t stack_size = getlim(RLIMIT_STACK);
+  return (stack_size == RLIM_INFINITY);
+}
+
+void SetStackSizeLimitInBytes(uptr limit) {
+  setlim(RLIMIT_STACK, (rlim_t)limit);
+  CHECK(!StackSizeIsUnlimited());
+}
+
+bool AddressSpaceIsUnlimited() {
+  rlim_t as_size = getlim(RLIMIT_AS);
+  return (as_size == RLIM_INFINITY);
+}
+
+void SetAddressSpaceUnlimited() {
+  setlim(RLIMIT_AS, RLIM_INFINITY);
+  CHECK(AddressSpaceIsUnlimited());
+}
+
+void SleepForSeconds(int seconds) {
+  sleep(seconds);
+}
+
+void SleepForMillis(int millis) {
+  usleep(millis * 1000);
+}
+
+void Abort() {
+#if !SANITIZER_GO
+  // If we are handling SIGABRT, unhandle it first.
+  // TODO(vitalybuka): Check if handler belongs to sanitizer.
+  if (GetHandleSignalMode(SIGABRT) != kHandleSignalNo) {
+    struct sigaction sigact;
+    internal_memset(&sigact, 0, sizeof(sigact));
+    sigact.sa_sigaction = (sa_sigaction_t)SIG_DFL;
+    internal_sigaction(SIGABRT, &sigact, nullptr);
+  }
+#endif
+
+  abort();
+}
+
+int Atexit(void (*function)(void)) {
+#if !SANITIZER_GO
+  return atexit(function);
+#else
+  return 0;
+#endif
+}
+
+bool SupportsColoredOutput(fd_t fd) {
+  return isatty(fd) != 0;
+}
+
+#if !SANITIZER_GO
+// TODO(glider): different tools may require different altstack size.
+static const uptr kAltStackSize = SIGSTKSZ * 4;  // SIGSTKSZ is not enough.
+
+void SetAlternateSignalStack() {
+  stack_t altstack, oldstack;
+  CHECK_EQ(0, sigaltstack(nullptr, &oldstack));
+  // If the alternate stack is already in place, do nothing.
+  // Android always sets an alternate stack, but it's too small for us.
+  if (!SANITIZER_ANDROID && !(oldstack.ss_flags & SS_DISABLE)) return;
+  // TODO(glider): the mapped stack should have the MAP_STACK flag in the
+  // future. It is not required by man 2 sigaltstack now (they're using
+  // malloc()).
+  void* base = MmapOrDie(kAltStackSize, __func__);
+  altstack.ss_sp = (char*) base;
+  altstack.ss_flags = 0;
+  altstack.ss_size = kAltStackSize;
+  CHECK_EQ(0, sigaltstack(&altstack, nullptr));
+}
+
+void UnsetAlternateSignalStack() {
+  stack_t altstack, oldstack;
+  altstack.ss_sp = nullptr;
+  altstack.ss_flags = SS_DISABLE;
+  altstack.ss_size = kAltStackSize;  // Some sane value required on Darwin.
+  CHECK_EQ(0, sigaltstack(&altstack, &oldstack));
+  UnmapOrDie(oldstack.ss_sp, oldstack.ss_size);
+}
+
+static void MaybeInstallSigaction(int signum,
+                                  SignalHandlerType handler) {
+  if (GetHandleSignalMode(signum) == kHandleSignalNo) return;
+
+  struct sigaction sigact;
+  internal_memset(&sigact, 0, sizeof(sigact));
+  sigact.sa_sigaction = (sa_sigaction_t)handler;
+  // Do not block the signal from being received in that signal's handler.
+  // Clients are responsible for handling this correctly.
+  sigact.sa_flags = SA_SIGINFO | SA_NODEFER;
+  if (common_flags()->use_sigaltstack) sigact.sa_flags |= SA_ONSTACK;
+  CHECK_EQ(0, internal_sigaction(signum, &sigact, nullptr));
+  VReport(1, "Installed the sigaction for signal %d\n", signum);
+}
+
+void InstallDeadlySignalHandlers(SignalHandlerType handler) {
+  // Set the alternate signal stack for the main thread.
+  // This will cause SetAlternateSignalStack to be called twice, but the stack
+  // will be actually set only once.
+  if (common_flags()->use_sigaltstack) SetAlternateSignalStack();
+  MaybeInstallSigaction(SIGSEGV, handler);
+  MaybeInstallSigaction(SIGBUS, handler);
+  MaybeInstallSigaction(SIGABRT, handler);
+  MaybeInstallSigaction(SIGFPE, handler);
+  MaybeInstallSigaction(SIGILL, handler);
+  MaybeInstallSigaction(SIGTRAP, handler);
+}
+
+bool SignalContext::IsStackOverflow() const {
+  // Access at a reasonable offset above SP, or slightly below it (to account
+  // for x86_64 or PowerPC redzone, ARM push of multiple registers, etc) is
+  // probably a stack overflow.
+#ifdef __s390__
+  // On s390, the fault address in siginfo points to start of the page, not
+  // to the precise word that was accessed.  Mask off the low bits of sp to
+  // take it into account.
+  bool IsStackAccess = addr >= (sp & ~0xFFF) && addr < sp + 0xFFFF;
+#else
+  // Let's accept up to a page size away from top of stack. Things like stack
+  // probing can trigger accesses with such large offsets.
+  bool IsStackAccess = addr + GetPageSizeCached() > sp && addr < sp + 0xFFFF;
+#endif
+
+#if __powerpc__
+  // Large stack frames can be allocated with e.g.
+  //   lis r0,-10000
+  //   stdux r1,r1,r0 # store sp to [sp-10000] and update sp by -10000
+  // If the store faults then sp will not have been updated, so test above
+  // will not work, because the fault address will be more than just "slightly"
+  // below sp.
+  if (!IsStackAccess && IsAccessibleMemoryRange(pc, 4)) {
+    u32 inst = *(unsigned *)pc;
+    u32 ra = (inst >> 16) & 0x1F;
+    u32 opcd = inst >> 26;
+    u32 xo = (inst >> 1) & 0x3FF;
+    // Check for store-with-update to sp. The instructions we accept are:
+    //   stbu rs,d(ra)          stbux rs,ra,rb
+    //   sthu rs,d(ra)          sthux rs,ra,rb
+    //   stwu rs,d(ra)          stwux rs,ra,rb
+    //   stdu rs,ds(ra)         stdux rs,ra,rb
+    // where ra is r1 (the stack pointer).
+    if (ra == 1 &&
+        (opcd == 39 || opcd == 45 || opcd == 37 || opcd == 62 ||
+         (opcd == 31 && (xo == 247 || xo == 439 || xo == 183 || xo == 181))))
+      IsStackAccess = true;
+  }
+#endif  // __powerpc__
+
+  // We also check si_code to filter out SEGV caused by something else other
+  // then hitting the guard page or unmapped memory, like, for example,
+  // unaligned memory access.
+  auto si = static_cast<const siginfo_t *>(siginfo);
+  return IsStackAccess &&
+         (si->si_code == si_SEGV_MAPERR || si->si_code == si_SEGV_ACCERR);
+}
+
+#endif  // SANITIZER_GO
+
+bool IsAccessibleMemoryRange(uptr beg, uptr size) {
+  uptr page_size = GetPageSizeCached();
+  // Checking too large memory ranges is slow.
+  CHECK_LT(size, page_size * 10);
+  int sock_pair[2];
+  if (pipe(sock_pair))
+    return false;
+  uptr bytes_written =
+      internal_write(sock_pair[1], reinterpret_cast<void *>(beg), size);
+  int write_errno;
+  bool result;
+  if (internal_iserror(bytes_written, &write_errno)) {
+    CHECK_EQ(EFAULT, write_errno);
+    result = false;
+  } else {
+    result = (bytes_written == size);
+  }
+  internal_close(sock_pair[0]);
+  internal_close(sock_pair[1]);
+  return result;
+}
+
+void PlatformPrepareForSandboxing(__sanitizer_sandbox_arguments *args) {
+  // Some kinds of sandboxes may forbid filesystem access, so we won't be able
+  // to read the file mappings from /proc/self/maps. Luckily, neither the
+  // process will be able to load additional libraries, so it's fine to use the
+  // cached mappings.
+  MemoryMappingLayout::CacheMemoryMappings();
+}
+
+static bool MmapFixed(uptr fixed_addr, uptr size, int additional_flags,
+                      const char *name) {
+  size = RoundUpTo(size, GetPageSizeCached());
+  fixed_addr = RoundDownTo(fixed_addr, GetPageSizeCached());
+  uptr p =
+      MmapNamed((void *)fixed_addr, size, PROT_READ | PROT_WRITE,
+                MAP_PRIVATE | MAP_FIXED | additional_flags | MAP_ANON, name);
+  int reserrno;
+  if (internal_iserror(p, &reserrno)) {
+    Report("ERROR: %s failed to "
+           "allocate 0x%zx (%zd) bytes at address %zx (errno: %d)\n",
+           SanitizerToolName, size, size, fixed_addr, reserrno);
+    return false;
+  }
+  IncreaseTotalMmap(size);
+  return true;
+}
+
+bool MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
+  return MmapFixed(fixed_addr, size, MAP_NORESERVE, name);
+}
+
+bool MmapFixedSuperNoReserve(uptr fixed_addr, uptr size, const char *name) {
+#if SANITIZER_FREEBSD
+  if (common_flags()->no_huge_pages_for_shadow)
+    return MmapFixedNoReserve(fixed_addr, size, name);
+  // MAP_NORESERVE is implicit with FreeBSD
+  return MmapFixed(fixed_addr, size, MAP_ALIGNED_SUPER, name);
+#else
+  bool r = MmapFixedNoReserve(fixed_addr, size, name);
+  if (r)
+    SetShadowRegionHugePageMode(fixed_addr, size);
+  return r;
+#endif
+}
+
+uptr ReservedAddressRange::Init(uptr size, const char *name, uptr fixed_addr) {
+  base_ = fixed_addr ? MmapFixedNoAccess(fixed_addr, size, name)
+                     : MmapNoAccess(size);
+  size_ = size;
+  name_ = name;
+  (void)os_handle_;  // unsupported
+  return reinterpret_cast<uptr>(base_);
+}
+
+// Uses fixed_addr for now.
+// Will use offset instead once we've implemented this function for real.
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr size, const char *name) {
+  return reinterpret_cast<uptr>(
+      MmapFixedOrDieOnFatalError(fixed_addr, size, name));
+}
+
+uptr ReservedAddressRange::MapOrDie(uptr fixed_addr, uptr size,
+                                    const char *name) {
+  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, size, name));
+}
+
+void ReservedAddressRange::Unmap(uptr addr, uptr size) {
+  CHECK_LE(size, size_);
+  if (addr == reinterpret_cast<uptr>(base_))
+    // If we unmap the whole range, just null out the base.
+    base_ = (size == size_) ? nullptr : reinterpret_cast<void*>(addr + size);
+  else
+    CHECK_EQ(addr + size, reinterpret_cast<uptr>(base_) + size_);
+  size_ -= size;
+  UnmapOrDie(reinterpret_cast<void*>(addr), size);
+}
+
+void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
+  return (void *)MmapNamed((void *)fixed_addr, size, PROT_NONE,
+                           MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE | MAP_ANON,
+                           name);
+}
+
+void *MmapNoAccess(uptr size) {
+  unsigned flags = MAP_PRIVATE | MAP_ANON | MAP_NORESERVE;
+  return (void *)internal_mmap(nullptr, size, PROT_NONE, flags, -1, 0);
+}
+
+// This function is defined elsewhere if we intercepted pthread_attr_getstack.
+extern "C" {
+SANITIZER_WEAK_ATTRIBUTE int
+real_pthread_attr_getstack(void *attr, void **addr, size_t *size);
+} // extern "C"
+
+int my_pthread_attr_getstack(void *attr, void **addr, uptr *size) {
+#if !SANITIZER_GO && !SANITIZER_MAC
+  if (&real_pthread_attr_getstack)
+    return real_pthread_attr_getstack((pthread_attr_t *)attr, addr,
+                                      (size_t *)size);
+#endif
+  return pthread_attr_getstack((pthread_attr_t *)attr, addr, (size_t *)size);
+}
+
+#if !SANITIZER_GO
+void AdjustStackSize(void *attr_) {
+  pthread_attr_t *attr = (pthread_attr_t *)attr_;
+  uptr stackaddr = 0;
+  uptr stacksize = 0;
+  my_pthread_attr_getstack(attr, (void**)&stackaddr, &stacksize);
+  // GLibC will return (0 - stacksize) as the stack address in the case when
+  // stacksize is set, but stackaddr is not.
+  bool stack_set = (stackaddr != 0) && (stackaddr + stacksize != 0);
+  // We place a lot of tool data into TLS, account for that.
+  const uptr minstacksize = GetTlsSize() + 128*1024;
+  if (stacksize < minstacksize) {
+    if (!stack_set) {
+      if (stacksize != 0) {
+        VPrintf(1, "Sanitizer: increasing stacksize %zu->%zu\n", stacksize,
+                minstacksize);
+        pthread_attr_setstacksize(attr, minstacksize);
+      }
+    } else {
+      Printf("Sanitizer: pre-allocated stack size is insufficient: "
+             "%zu < %zu\n", stacksize, minstacksize);
+      Printf("Sanitizer: pthread_create is likely to fail.\n");
+    }
+  }
+}
+#endif // !SANITIZER_GO
+
+pid_t StartSubprocess(const char *program, const char *const argv[],
+                      const char *const envp[], fd_t stdin_fd, fd_t stdout_fd,
+                      fd_t stderr_fd) {
+  auto file_closer = at_scope_exit([&] {
+    if (stdin_fd != kInvalidFd) {
+      internal_close(stdin_fd);
+    }
+    if (stdout_fd != kInvalidFd) {
+      internal_close(stdout_fd);
+    }
+    if (stderr_fd != kInvalidFd) {
+      internal_close(stderr_fd);
+    }
+  });
+
+  int pid = internal_fork();
+
+  if (pid < 0) {
+    int rverrno;
+    if (internal_iserror(pid, &rverrno)) {
+      Report("WARNING: failed to fork (errno %d)\n", rverrno);
+    }
+    return pid;
+  }
+
+  if (pid == 0) {
+    // Child subprocess
+    if (stdin_fd != kInvalidFd) {
+      internal_close(STDIN_FILENO);
+      internal_dup2(stdin_fd, STDIN_FILENO);
+      internal_close(stdin_fd);
+    }
+    if (stdout_fd != kInvalidFd) {
+      internal_close(STDOUT_FILENO);
+      internal_dup2(stdout_fd, STDOUT_FILENO);
+      internal_close(stdout_fd);
+    }
+    if (stderr_fd != kInvalidFd) {
+      internal_close(STDERR_FILENO);
+      internal_dup2(stderr_fd, STDERR_FILENO);
+      internal_close(stderr_fd);
+    }
+
+    for (int fd = sysconf(_SC_OPEN_MAX); fd > 2; fd--) internal_close(fd);
+
+    internal_execve(program, const_cast<char **>(&argv[0]),
+                    const_cast<char *const *>(envp));
+    internal__exit(1);
+  }
+
+  return pid;
+}
+
+bool IsProcessRunning(pid_t pid) {
+  int process_status;
+  uptr waitpid_status = internal_waitpid(pid, &process_status, WNOHANG);
+  int local_errno;
+  if (internal_iserror(waitpid_status, &local_errno)) {
+    VReport(1, "Waiting on the process failed (errno %d).\n", local_errno);
+    return false;
+  }
+  return waitpid_status == 0;
+}
+
+int WaitForProcess(pid_t pid) {
+  int process_status;
+  uptr waitpid_status = internal_waitpid(pid, &process_status, 0);
+  int local_errno;
+  if (internal_iserror(waitpid_status, &local_errno)) {
+    VReport(1, "Waiting on the process failed (errno %d).\n", local_errno);
+    return -1;
+  }
+  return process_status;
+}
+
+bool IsStateDetached(int state) {
+  return state == PTHREAD_CREATE_DETACHED;
+}
+
+} // namespace __sanitizer
+
+#endif // SANITIZER_POSIX
diff --git a/lib/tsan/sanitizer_common/sanitizer_stackdepot.cpp b/lib/tsan/sanitizer_common/sanitizer_stackdepot.cpp
new file mode 100644
index 0000000000..30073a96ce
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_stackdepot.cpp
@@ -0,0 +1,149 @@
+//===-- sanitizer_stackdepot.cpp ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_stackdepot.h"
+
+#include "sanitizer_common.h"
+#include "sanitizer_hash.h"
+#include "sanitizer_stackdepotbase.h"
+
+namespace __sanitizer {
+
+struct StackDepotNode {
+  StackDepotNode *link;
+  u32 id;
+  atomic_uint32_t hash_and_use_count; // hash_bits : 12; use_count : 20;
+  u32 size;
+  u32 tag;
+  uptr stack[1];  // [size]
+
+  static const u32 kTabSizeLog = SANITIZER_ANDROID ? 16 : 20;
+  // Lower kTabSizeLog bits are equal for all items in one bucket.
+  // We use these bits to store the per-stack use counter.
+  static const u32 kUseCountBits = kTabSizeLog;
+  static const u32 kMaxUseCount = 1 << kUseCountBits;
+  static const u32 kUseCountMask = (1 << kUseCountBits) - 1;
+  static const u32 kHashMask = ~kUseCountMask;
+
+  typedef StackTrace args_type;
+  bool eq(u32 hash, const args_type &args) const {
+    u32 hash_bits =
+        atomic_load(&hash_and_use_count, memory_order_relaxed) & kHashMask;
+    if ((hash & kHashMask) != hash_bits || args.size != size || args.tag != tag)
+      return false;
+    uptr i = 0;
+    for (; i < size; i++) {
+      if (stack[i] != args.trace[i]) return false;
+    }
+    return true;
+  }
+  static uptr storage_size(const args_type &args) {
+    return sizeof(StackDepotNode) + (args.size - 1) * sizeof(uptr);
+  }
+  static u32 hash(const args_type &args) {
+    MurMur2HashBuilder H(args.size * sizeof(uptr));
+    for (uptr i = 0; i < args.size; i++) H.add(args.trace[i]);
+    return H.get();
+  }
+  static bool is_valid(const args_type &args) {
+    return args.size > 0 && args.trace;
+  }
+  void store(const args_type &args, u32 hash) {
+    atomic_store(&hash_and_use_count, hash & kHashMask, memory_order_relaxed);
+    size = args.size;
+    tag = args.tag;
+    internal_memcpy(stack, args.trace, size * sizeof(uptr));
+  }
+  args_type load() const {
+    return args_type(&stack[0], size, tag);
+  }
+  StackDepotHandle get_handle() { return StackDepotHandle(this); }
+
+  typedef StackDepotHandle handle_type;
+};
+
+COMPILER_CHECK(StackDepotNode::kMaxUseCount == (u32)kStackDepotMaxUseCount);
+
+u32 StackDepotHandle::id() { return node_->id; }
+int StackDepotHandle::use_count() {
+  return atomic_load(&node_->hash_and_use_count, memory_order_relaxed) &
+         StackDepotNode::kUseCountMask;
+}
+void StackDepotHandle::inc_use_count_unsafe() {
+  u32 prev =
+      atomic_fetch_add(&node_->hash_and_use_count, 1, memory_order_relaxed) &
+      StackDepotNode::kUseCountMask;
+  CHECK_LT(prev + 1, StackDepotNode::kMaxUseCount);
+}
+
+// FIXME(dvyukov): this single reserved bit is used in TSan.
+typedef StackDepotBase<StackDepotNode, 1, StackDepotNode::kTabSizeLog>
+    StackDepot;
+static StackDepot theDepot;
+
+StackDepotStats *StackDepotGetStats() {
+  return theDepot.GetStats();
+}
+
+u32 StackDepotPut(StackTrace stack) {
+  StackDepotHandle h = theDepot.Put(stack);
+  return h.valid() ? h.id() : 0;
+}
+
+StackDepotHandle StackDepotPut_WithHandle(StackTrace stack) {
+  return theDepot.Put(stack);
+}
+
+StackTrace StackDepotGet(u32 id) {
+  return theDepot.Get(id);
+}
+
+void StackDepotLockAll() {
+  theDepot.LockAll();
+}
+
+void StackDepotUnlockAll() {
+  theDepot.UnlockAll();
+}
+
+bool StackDepotReverseMap::IdDescPair::IdComparator(
+    const StackDepotReverseMap::IdDescPair &a,
+    const StackDepotReverseMap::IdDescPair &b) {
+  return a.id < b.id;
+}
+
+StackDepotReverseMap::StackDepotReverseMap() {
+  map_.reserve(StackDepotGetStats()->n_uniq_ids + 100);
+  for (int idx = 0; idx < StackDepot::kTabSize; idx++) {
+    atomic_uintptr_t *p = &theDepot.tab[idx];
+    uptr v = atomic_load(p, memory_order_consume);
+    StackDepotNode *s = (StackDepotNode*)(v & ~1);
+    for (; s; s = s->link) {
+      IdDescPair pair = {s->id, s};
+      map_.push_back(pair);
+    }
+  }
+  Sort(map_.data(), map_.size(), &IdDescPair::IdComparator);
+}
+
+StackTrace StackDepotReverseMap::Get(u32 id) {
+  if (!map_.size())
+    return StackTrace();
+  IdDescPair pair = {id, nullptr};
+  uptr idx =
+      InternalLowerBound(map_, 0, map_.size(), pair, IdDescPair::IdComparator);
+  if (idx > map_.size() || map_[idx].id != id)
+    return StackTrace();
+  return map_[idx].desc->load();
+}
+
+} // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_stacktrace.cpp b/lib/tsan/sanitizer_common/sanitizer_stacktrace.cpp
new file mode 100644
index 0000000000..ef14fb704e
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_stacktrace.cpp
@@ -0,0 +1,133 @@
+//===-- sanitizer_stacktrace.cpp ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_stacktrace.h"
+
+namespace __sanitizer {
+
+uptr StackTrace::GetNextInstructionPc(uptr pc) {
+#if defined(__sparc__) || defined(__mips__)
+  return pc + 8;
+#elif defined(__powerpc__) || defined(__arm__) || defined(__aarch64__)
+  return pc + 4;
+#else
+  return pc + 1;
+#endif
+}
+
+uptr StackTrace::GetCurrentPc() {
+  return GET_CALLER_PC();
+}
+
+void BufferedStackTrace::Init(const uptr *pcs, uptr cnt, uptr extra_top_pc) {
+  size = cnt + !!extra_top_pc;
+  CHECK_LE(size, kStackTraceMax);
+  internal_memcpy(trace_buffer, pcs, cnt * sizeof(trace_buffer[0]));
+  if (extra_top_pc)
+    trace_buffer[cnt] = extra_top_pc;
+  top_frame_bp = 0;
+}
+
+// Sparc implemention is in its own file.
+#if !defined(__sparc__)
+
+// In GCC on ARM bp points to saved lr, not fp, so we should check the next
+// cell in stack to be a saved frame pointer. GetCanonicFrame returns the
+// pointer to saved frame pointer in any case.
+static inline uhwptr *GetCanonicFrame(uptr bp,
+                                      uptr stack_top,
+                                      uptr stack_bottom) {
+  CHECK_GT(stack_top, stack_bottom);
+#ifdef __arm__
+  if (!IsValidFrame(bp, stack_top, stack_bottom)) return 0;
+  uhwptr *bp_prev = (uhwptr *)bp;
+  if (IsValidFrame((uptr)bp_prev[0], stack_top, stack_bottom)) return bp_prev;
+  // The next frame pointer does not look right. This could be a GCC frame, step
+  // back by 1 word and try again.
+  if (IsValidFrame((uptr)bp_prev[-1], stack_top, stack_bottom))
+    return bp_prev - 1;
+  // Nope, this does not look right either. This means the frame after next does
+  // not have a valid frame pointer, but we can still extract the caller PC.
+  // Unfortunately, there is no way to decide between GCC and LLVM frame
+  // layouts. Assume LLVM.
+  return bp_prev;
+#else
+  return (uhwptr*)bp;
+#endif
+}
+
+void BufferedStackTrace::UnwindFast(uptr pc, uptr bp, uptr stack_top,
+                                    uptr stack_bottom, u32 max_depth) {
+  // TODO(yln): add arg sanity check for stack_top/stack_bottom
+  CHECK_GE(max_depth, 2);
+  const uptr kPageSize = GetPageSizeCached();
+  trace_buffer[0] = pc;
+  size = 1;
+  if (stack_top < 4096) return;  // Sanity check for stack top.
+  uhwptr *frame = GetCanonicFrame(bp, stack_top, stack_bottom);
+  // Lowest possible address that makes sense as the next frame pointer.
+  // Goes up as we walk the stack.
+  uptr bottom = stack_bottom;
+  // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
+  while (IsValidFrame((uptr)frame, stack_top, bottom) &&
+         IsAligned((uptr)frame, sizeof(*frame)) &&
+         size < max_depth) {
+#ifdef __powerpc__
+    // PowerPC ABIs specify that the return address is saved at offset
+    // 16 of the *caller's* stack frame.  Thus we must dereference the
+    // back chain to find the caller frame before extracting it.
+    uhwptr *caller_frame = (uhwptr*)frame[0];
+    if (!IsValidFrame((uptr)caller_frame, stack_top, bottom) ||
+        !IsAligned((uptr)caller_frame, sizeof(uhwptr)))
+      break;
+    uhwptr pc1 = caller_frame[2];
+#elif defined(__s390__)
+    uhwptr pc1 = frame[14];
+#else
+    uhwptr pc1 = frame[1];
+#endif
+    // Let's assume that any pointer in the 0th page (i.e. <0x1000 on i386 and
+    // x86_64) is invalid and stop unwinding here.  If we're adding support for
+    // a platform where this isn't true, we need to reconsider this check.
+    if (pc1 < kPageSize)
+      break;
+    if (pc1 != pc) {
+      trace_buffer[size++] = (uptr) pc1;
+    }
+    bottom = (uptr)frame;
+    frame = GetCanonicFrame((uptr)frame[0], stack_top, bottom);
+  }
+}
+
+#endif  // !defined(__sparc__)
+
+void BufferedStackTrace::PopStackFrames(uptr count) {
+  CHECK_LT(count, size);
+  size -= count;
+  for (uptr i = 0; i < size; ++i) {
+    trace_buffer[i] = trace_buffer[i + count];
+  }
+}
+
+static uptr Distance(uptr a, uptr b) { return a < b ? b - a : a - b; }
+
+uptr BufferedStackTrace::LocatePcInTrace(uptr pc) {
+  uptr best = 0;
+  for (uptr i = 1; i < size; ++i) {
+    if (Distance(trace[i], pc) < Distance(trace[best], pc)) best = i;
+  }
+  return best;
+}
+
+}  // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_stacktrace_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_stacktrace_libcdep.cpp
new file mode 100644
index 0000000000..4ef305cf17
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_stacktrace_libcdep.cpp
@@ -0,0 +1,159 @@
+//===-- sanitizer_stacktrace_libcdep.cpp ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common.h"
+#include "sanitizer_placement_new.h"
+#include "sanitizer_stacktrace.h"
+#include "sanitizer_stacktrace_printer.h"
+#include "sanitizer_symbolizer.h"
+
+namespace __sanitizer {
+
+void StackTrace::Print() const {
+  if (trace == nullptr || size == 0) {
+    Printf("    <empty stack>\n\n");
+    return;
+  }
+  InternalScopedString frame_desc(GetPageSizeCached() * 2);
+  InternalScopedString dedup_token(GetPageSizeCached());
+  int dedup_frames = common_flags()->dedup_token_length;
+  uptr frame_num = 0;
+  for (uptr i = 0; i < size && trace[i]; i++) {
+    // PCs in stack traces are actually the return addresses, that is,
+    // addresses of the next instructions after the call.
+    uptr pc = GetPreviousInstructionPc(trace[i]);
+    SymbolizedStack *frames = Symbolizer::GetOrInit()->SymbolizePC(pc);
+    CHECK(frames);
+    for (SymbolizedStack *cur = frames; cur; cur = cur->next) {
+      frame_desc.clear();
+      RenderFrame(&frame_desc, common_flags()->stack_trace_format, frame_num++,
+                  cur->info, common_flags()->symbolize_vs_style,
+                  common_flags()->strip_path_prefix);
+      Printf("%s\n", frame_desc.data());
+      if (dedup_frames-- > 0) {
+        if (dedup_token.length())
+          dedup_token.append("--");
+        if (cur->info.function != nullptr)
+          dedup_token.append(cur->info.function);
+      }
+    }
+    frames->ClearAll();
+  }
+  // Always print a trailing empty line after stack trace.
+  Printf("\n");
+  if (dedup_token.length())
+    Printf("DEDUP_TOKEN: %s\n", dedup_token.data());
+}
+
+void BufferedStackTrace::Unwind(u32 max_depth, uptr pc, uptr bp, void *context,
+                                uptr stack_top, uptr stack_bottom,
+                                bool request_fast_unwind) {
+  // Ensures all call sites get what they requested.
+  CHECK_EQ(request_fast_unwind, WillUseFastUnwind(request_fast_unwind));
+  top_frame_bp = (max_depth > 0) ? bp : 0;
+  // Avoid doing any work for small max_depth.
+  if (max_depth == 0) {
+    size = 0;
+    return;
+  }
+  if (max_depth == 1) {
+    size = 1;
+    trace_buffer[0] = pc;
+    return;
+  }
+  if (!WillUseFastUnwind(request_fast_unwind)) {
+#if SANITIZER_CAN_SLOW_UNWIND
+    if (context)
+      UnwindSlow(pc, context, max_depth);
+    else
+      UnwindSlow(pc, max_depth);
+#else
+    UNREACHABLE("slow unwind requested but not available");
+#endif
+  } else {
+    UnwindFast(pc, bp, stack_top, stack_bottom, max_depth);
+  }
+}
+
+static int GetModuleAndOffsetForPc(uptr pc, char *module_name,
+                                   uptr module_name_len, uptr *pc_offset) {
+  const char *found_module_name = nullptr;
+  bool ok = Symbolizer::GetOrInit()->GetModuleNameAndOffsetForPC(
+      pc, &found_module_name, pc_offset);
+
+  if (!ok) return false;
+
+  if (module_name && module_name_len) {
+    internal_strncpy(module_name, found_module_name, module_name_len);
+    module_name[module_name_len - 1] = '\x00';
+  }
+  return true;
+}
+
+}  // namespace __sanitizer
+using namespace __sanitizer;
+
+extern "C" {
+SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_symbolize_pc(uptr pc, const char *fmt, char *out_buf,
+                              uptr out_buf_size) {
+  if (!out_buf_size) return;
+  pc = StackTrace::GetPreviousInstructionPc(pc);
+  SymbolizedStack *frame = Symbolizer::GetOrInit()->SymbolizePC(pc);
+  if (!frame) {
+    internal_strncpy(out_buf, "<can't symbolize>", out_buf_size);
+    out_buf[out_buf_size - 1] = 0;
+    return;
+  }
+  InternalScopedString frame_desc(GetPageSizeCached());
+  uptr frame_num = 0;
+  // Reserve one byte for the final 0.
+  char *out_end = out_buf + out_buf_size - 1;
+  for (SymbolizedStack *cur = frame; cur && out_buf < out_end;
+       cur = cur->next) {
+    frame_desc.clear();
+    RenderFrame(&frame_desc, fmt, frame_num++, cur->info,
+                common_flags()->symbolize_vs_style,
+                common_flags()->strip_path_prefix);
+    if (!frame_desc.length())
+      continue;
+    // Reserve one byte for the terminating 0.
+    uptr n = out_end - out_buf - 1;
+    internal_strncpy(out_buf, frame_desc.data(), n);
+    out_buf += __sanitizer::Min<uptr>(n, frame_desc.length());
+    *out_buf++ = 0;
+  }
+  CHECK(out_buf <= out_end);
+  *out_buf = 0;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_symbolize_global(uptr data_addr, const char *fmt,
+                                  char *out_buf, uptr out_buf_size) {
+  if (!out_buf_size) return;
+  out_buf[0] = 0;
+  DataInfo DI;
+  if (!Symbolizer::GetOrInit()->SymbolizeData(data_addr, &DI)) return;
+  InternalScopedString data_desc(GetPageSizeCached());
+  RenderData(&data_desc, fmt, &DI, common_flags()->strip_path_prefix);
+  internal_strncpy(out_buf, data_desc.data(), out_buf_size);
+  out_buf[out_buf_size - 1] = 0;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE
+int __sanitizer_get_module_and_offset_for_pc(uptr pc, char *module_name,
+                                             uptr module_name_len,
+                                             uptr *pc_offset) {
+  return __sanitizer::GetModuleAndOffsetForPc(pc, module_name, module_name_len,
+                                              pc_offset);
+}
+}  // extern "C"
diff --git a/lib/tsan/sanitizer_common/sanitizer_stacktrace_printer.cpp b/lib/tsan/sanitizer_common/sanitizer_stacktrace_printer.cpp
new file mode 100644
index 0000000000..150ff47531
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_stacktrace_printer.cpp
@@ -0,0 +1,263 @@
+//===-- sanitizer_common.cpp ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between sanitizers' run-time libraries.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_stacktrace_printer.h"
+#include "sanitizer_file.h"
+#include "sanitizer_fuchsia.h"
+
+namespace __sanitizer {
+
+// sanitizer_symbolizer_markup.cpp implements these differently.
+#if !SANITIZER_SYMBOLIZER_MARKUP
+
+static const char *StripFunctionName(const char *function, const char *prefix) {
+  if (!function) return nullptr;
+  if (!prefix) return function;
+  uptr prefix_len = internal_strlen(prefix);
+  if (0 == internal_strncmp(function, prefix, prefix_len))
+    return function + prefix_len;
+  return function;
+}
+
+static const char *DemangleFunctionName(const char *function) {
+  if (!function) return nullptr;
+
+  // NetBSD uses indirection for old threading functions for historical reasons
+  // The mangled names are internal implementation detail and should not be
+  // exposed even in backtraces.
+#if SANITIZER_NETBSD
+  if (!internal_strcmp(function, "__libc_mutex_init"))
+    return "pthread_mutex_init";
+  if (!internal_strcmp(function, "__libc_mutex_lock"))
+    return "pthread_mutex_lock";
+  if (!internal_strcmp(function, "__libc_mutex_trylock"))
+    return "pthread_mutex_trylock";
+  if (!internal_strcmp(function, "__libc_mutex_unlock"))
+    return "pthread_mutex_unlock";
+  if (!internal_strcmp(function, "__libc_mutex_destroy"))
+    return "pthread_mutex_destroy";
+  if (!internal_strcmp(function, "__libc_mutexattr_init"))
+    return "pthread_mutexattr_init";
+  if (!internal_strcmp(function, "__libc_mutexattr_settype"))
+    return "pthread_mutexattr_settype";
+  if (!internal_strcmp(function, "__libc_mutexattr_destroy"))
+    return "pthread_mutexattr_destroy";
+  if (!internal_strcmp(function, "__libc_cond_init"))
+    return "pthread_cond_init";
+  if (!internal_strcmp(function, "__libc_cond_signal"))
+    return "pthread_cond_signal";
+  if (!internal_strcmp(function, "__libc_cond_broadcast"))
+    return "pthread_cond_broadcast";
+  if (!internal_strcmp(function, "__libc_cond_wait"))
+    return "pthread_cond_wait";
+  if (!internal_strcmp(function, "__libc_cond_timedwait"))
+    return "pthread_cond_timedwait";
+  if (!internal_strcmp(function, "__libc_cond_destroy"))
+    return "pthread_cond_destroy";
+  if (!internal_strcmp(function, "__libc_rwlock_init"))
+    return "pthread_rwlock_init";
+  if (!internal_strcmp(function, "__libc_rwlock_rdlock"))
+    return "pthread_rwlock_rdlock";
+  if (!internal_strcmp(function, "__libc_rwlock_wrlock"))
+    return "pthread_rwlock_wrlock";
+  if (!internal_strcmp(function, "__libc_rwlock_tryrdlock"))
+    return "pthread_rwlock_tryrdlock";
+  if (!internal_strcmp(function, "__libc_rwlock_trywrlock"))
+    return "pthread_rwlock_trywrlock";
+  if (!internal_strcmp(function, "__libc_rwlock_unlock"))
+    return "pthread_rwlock_unlock";
+  if (!internal_strcmp(function, "__libc_rwlock_destroy"))
+    return "pthread_rwlock_destroy";
+  if (!internal_strcmp(function, "__libc_thr_keycreate"))
+    return "pthread_key_create";
+  if (!internal_strcmp(function, "__libc_thr_setspecific"))
+    return "pthread_setspecific";
+  if (!internal_strcmp(function, "__libc_thr_getspecific"))
+    return "pthread_getspecific";
+  if (!internal_strcmp(function, "__libc_thr_keydelete"))
+    return "pthread_key_delete";
+  if (!internal_strcmp(function, "__libc_thr_once"))
+    return "pthread_once";
+  if (!internal_strcmp(function, "__libc_thr_self"))
+    return "pthread_self";
+  if (!internal_strcmp(function, "__libc_thr_exit"))
+    return "pthread_exit";
+  if (!internal_strcmp(function, "__libc_thr_setcancelstate"))
+    return "pthread_setcancelstate";
+  if (!internal_strcmp(function, "__libc_thr_equal"))
+    return "pthread_equal";
+  if (!internal_strcmp(function, "__libc_thr_curcpu"))
+    return "pthread_curcpu_np";
+  if (!internal_strcmp(function, "__libc_thr_sigsetmask"))
+    return "pthread_sigmask";
+#endif
+
+  return function;
+}
+
+static const char kDefaultFormat[] = "    #%n %p %F %L";
+
+void RenderFrame(InternalScopedString *buffer, const char *format, int frame_no,
+                 const AddressInfo &info, bool vs_style,
+                 const char *strip_path_prefix, const char *strip_func_prefix) {
+  if (0 == internal_strcmp(format, "DEFAULT"))
+    format = kDefaultFormat;
+  for (const char *p = format; *p != '\0'; p++) {
+    if (*p != '%') {
+      buffer->append("%c", *p);
+      continue;
+    }
+    p++;
+    switch (*p) {
+    case '%':
+      buffer->append("%%");
+      break;
+    // Frame number and all fields of AddressInfo structure.
+    case 'n':
+      buffer->append("%zu", frame_no);
+      break;
+    case 'p':
+      buffer->append("0x%zx", info.address);
+      break;
+    case 'm':
+      buffer->append("%s", StripPathPrefix(info.module, strip_path_prefix));
+      break;
+    case 'o':
+      buffer->append("0x%zx", info.module_offset);
+      break;
+    case 'f':
+      buffer->append("%s",
+        DemangleFunctionName(
+          StripFunctionName(info.function, strip_func_prefix)));
+      break;
+    case 'q':
+      buffer->append("0x%zx", info.function_offset != AddressInfo::kUnknown
+                                  ? info.function_offset
+                                  : 0x0);
+      break;
+    case 's':
+      buffer->append("%s", StripPathPrefix(info.file, strip_path_prefix));
+      break;
+    case 'l':
+      buffer->append("%d", info.line);
+      break;
+    case 'c':
+      buffer->append("%d", info.column);
+      break;
+    // Smarter special cases.
+    case 'F':
+      // Function name and offset, if file is unknown.
+      if (info.function) {
+        buffer->append("in %s",
+                       DemangleFunctionName(
+                         StripFunctionName(info.function, strip_func_prefix)));
+        if (!info.file && info.function_offset != AddressInfo::kUnknown)
+          buffer->append("+0x%zx", info.function_offset);
+      }
+      break;
+    case 'S':
+      // File/line information.
+      RenderSourceLocation(buffer, info.file, info.line, info.column, vs_style,
+                           strip_path_prefix);
+      break;
+    case 'L':
+      // Source location, or module location.
+      if (info.file) {
+        RenderSourceLocation(buffer, info.file, info.line, info.column,
+                             vs_style, strip_path_prefix);
+      } else if (info.module) {
+        RenderModuleLocation(buffer, info.module, info.module_offset,
+                             info.module_arch, strip_path_prefix);
+      } else {
+        buffer->append("(<unknown module>)");
+      }
+      break;
+    case 'M':
+      // Module basename and offset, or PC.
+      if (info.address & kExternalPCBit)
+        {} // There PCs are not meaningful.
+      else if (info.module)
+        // Always strip the module name for %M.
+        RenderModuleLocation(buffer, StripModuleName(info.module),
+                             info.module_offset, info.module_arch, "");
+      else
+        buffer->append("(%p)", (void *)info.address);
+      break;
+    default:
+      Report("Unsupported specifier in stack frame format: %c (0x%zx)!\n", *p,
+             *p);
+      Die();
+    }
+  }
+}
+
+void RenderData(InternalScopedString *buffer, const char *format,
+                const DataInfo *DI, const char *strip_path_prefix) {
+  for (const char *p = format; *p != '\0'; p++) {
+    if (*p != '%') {
+      buffer->append("%c", *p);
+      continue;
+    }
+    p++;
+    switch (*p) {
+      case '%':
+        buffer->append("%%");
+        break;
+      case 's':
+        buffer->append("%s", StripPathPrefix(DI->file, strip_path_prefix));
+        break;
+      case 'l':
+        buffer->append("%d", DI->line);
+        break;
+      case 'g':
+        buffer->append("%s", DI->name);
+        break;
+      default:
+        Report("Unsupported specifier in stack frame format: %c (0x%zx)!\n", *p,
+               *p);
+        Die();
+    }
+  }
+}
+
+#endif  // !SANITIZER_SYMBOLIZER_MARKUP
+
+void RenderSourceLocation(InternalScopedString *buffer, const char *file,
+                          int line, int column, bool vs_style,
+                          const char *strip_path_prefix) {
+  if (vs_style && line > 0) {
+    buffer->append("%s(%d", StripPathPrefix(file, strip_path_prefix), line);
+    if (column > 0)
+      buffer->append(",%d", column);
+    buffer->append(")");
+    return;
+  }
+
+  buffer->append("%s", StripPathPrefix(file, strip_path_prefix));
+  if (line > 0) {
+    buffer->append(":%d", line);
+    if (column > 0)
+      buffer->append(":%d", column);
+  }
+}
+
+void RenderModuleLocation(InternalScopedString *buffer, const char *module,
+                          uptr offset, ModuleArch arch,
+                          const char *strip_path_prefix) {
+  buffer->append("(%s", StripPathPrefix(module, strip_path_prefix));
+  if (arch != kModuleArchUnknown) {
+    buffer->append(":%s", ModuleArchToString(arch));
+  }
+  buffer->append("+0x%zx)", offset);
+}
+
+} // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_stacktrace_sparc.cpp b/lib/tsan/sanitizer_common/sanitizer_stacktrace_sparc.cpp
new file mode 100644
index 0000000000..34190fb1bb
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_stacktrace_sparc.cpp
@@ -0,0 +1,85 @@
+//===-- sanitizer_stacktrace_sparc.cpp ------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+//
+// Implemention of fast stack unwinding for Sparc.
+//===----------------------------------------------------------------------===//
+
+#if defined(__sparc__)
+
+#if defined(__arch64__) || defined(__sparcv9)
+#define STACK_BIAS 2047
+#else
+#define STACK_BIAS 0
+#endif
+
+#include "sanitizer_common.h"
+#include "sanitizer_stacktrace.h"
+
+namespace __sanitizer {
+
+void BufferedStackTrace::UnwindFast(uptr pc, uptr bp, uptr stack_top,
+                                    uptr stack_bottom, u32 max_depth) {
+  // TODO(yln): add arg sanity check for stack_top/stack_bottom
+  CHECK_GE(max_depth, 2);
+  const uptr kPageSize = GetPageSizeCached();
+#if defined(__GNUC__)
+  // __builtin_return_address returns the address of the call instruction
+  // on the SPARC and not the return address, so we need to compensate.
+  trace_buffer[0] = GetNextInstructionPc(pc);
+#else
+  trace_buffer[0] = pc;
+#endif
+  size = 1;
+  if (stack_top < 4096) return;  // Sanity check for stack top.
+  // Flush register windows to memory
+#if defined(__sparc_v9__) || defined(__sparcv9__) || defined(__sparcv9)
+  asm volatile("flushw" ::: "memory");
+#else
+  asm volatile("ta 3" ::: "memory");
+#endif
+  // On the SPARC, the return address is not in the frame, it is in a
+  // register.  There is no way to access it off of the current frame
+  // pointer, but it can be accessed off the previous frame pointer by
+  // reading the value from the register window save area.
+  uptr prev_bp = GET_CURRENT_FRAME();
+  uptr next_bp = prev_bp;
+  unsigned int i = 0;
+  while (next_bp != bp && IsAligned(next_bp, sizeof(uhwptr)) && i++ < 8) {
+    prev_bp = next_bp;
+    next_bp = (uptr)((uhwptr *)next_bp)[14] + STACK_BIAS;
+  }
+  if (next_bp == bp)
+    bp = prev_bp;
+  // Lowest possible address that makes sense as the next frame pointer.
+  // Goes up as we walk the stack.
+  uptr bottom = stack_bottom;
+  // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
+  while (IsValidFrame(bp, stack_top, bottom) && IsAligned(bp, sizeof(uhwptr)) &&
+         size < max_depth) {
+    uhwptr pc1 = ((uhwptr *)bp)[15];
+    // Let's assume that any pointer in the 0th page is invalid and
+    // stop unwinding here.  If we're adding support for a platform
+    // where this isn't true, we need to reconsider this check.
+    if (pc1 < kPageSize)
+      break;
+    if (pc1 != pc) {
+      // %o7 contains the address of the call instruction and not the
+      // return address, so we need to compensate.
+      trace_buffer[size++] = GetNextInstructionPc((uptr)pc1);
+    }
+    bottom = bp;
+    bp = (uptr)((uhwptr *)bp)[14] + STACK_BIAS;
+  }
+}
+
+}  // namespace __sanitizer
+
+#endif  // !defined(__sparc__)
diff --git a/lib/tsan/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp
new file mode 100644
index 0000000000..651d5056dd
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp
@@ -0,0 +1,573 @@
+//===-- sanitizer_stoptheworld_linux_libcdep.cpp --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// See sanitizer_stoptheworld.h for details.
+// This implementation was inspired by Markus Gutschke's linuxthreads.cc.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#if SANITIZER_LINUX && (defined(__x86_64__) || defined(__mips__) || \
+                        defined(__aarch64__) || defined(__powerpc64__) || \
+                        defined(__s390__) || defined(__i386__) || \
+                        defined(__arm__))
+
+#include "sanitizer_stoptheworld.h"
+
+#include "sanitizer_platform_limits_posix.h"
+#include "sanitizer_atomic.h"
+
+#include <errno.h>
+#include <sched.h> // for CLONE_* definitions
+#include <stddef.h>
+#include <sys/prctl.h> // for PR_* definitions
+#include <sys/ptrace.h> // for PTRACE_* definitions
+#include <sys/types.h> // for pid_t
+#include <sys/uio.h> // for iovec
+#include <elf.h> // for NT_PRSTATUS
+#if defined(__aarch64__) && !SANITIZER_ANDROID
+// GLIBC 2.20+ sys/user does not include asm/ptrace.h
+# include <asm/ptrace.h>
+#endif
+#include <sys/user.h>  // for user_regs_struct
+#if SANITIZER_ANDROID && SANITIZER_MIPS
+# include <asm/reg.h>  // for mips SP register in sys/user.h
+#endif
+#include <sys/wait.h> // for signal-related stuff
+
+#ifdef sa_handler
+# undef sa_handler
+#endif
+
+#ifdef sa_sigaction
+# undef sa_sigaction
+#endif
+
+#include "sanitizer_common.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_libc.h"
+#include "sanitizer_linux.h"
+#include "sanitizer_mutex.h"
+#include "sanitizer_placement_new.h"
+
+// Sufficiently old kernel headers don't provide this value, but we can still
+// call prctl with it. If the runtime kernel is new enough, the prctl call will
+// have the desired effect; if the kernel is too old, the call will error and we
+// can ignore said error.
+#ifndef PR_SET_PTRACER
+#define PR_SET_PTRACER 0x59616d61
+#endif
+
+// This module works by spawning a Linux task which then attaches to every
+// thread in the caller process with ptrace. This suspends the threads, and
+// PTRACE_GETREGS can then be used to obtain their register state. The callback
+// supplied to StopTheWorld() is run in the tracer task while the threads are
+// suspended.
+// The tracer task must be placed in a different thread group for ptrace to
+// work, so it cannot be spawned as a pthread. Instead, we use the low-level
+// clone() interface (we want to share the address space with the caller
+// process, so we prefer clone() over fork()).
+//
+// We don't use any libc functions, relying instead on direct syscalls. There
+// are two reasons for this:
+// 1. calling a library function while threads are suspended could cause a
+// deadlock, if one of the treads happens to be holding a libc lock;
+// 2. it's generally not safe to call libc functions from the tracer task,
+// because clone() does not set up a thread-local storage for it. Any
+// thread-local variables used by libc will be shared between the tracer task
+// and the thread which spawned it.
+
+namespace __sanitizer {
+
+class SuspendedThreadsListLinux : public SuspendedThreadsList {
+ public:
+  SuspendedThreadsListLinux() { thread_ids_.reserve(1024); }
+
+  tid_t GetThreadID(uptr index) const;
+  uptr ThreadCount() const;
+  bool ContainsTid(tid_t thread_id) const;
+  void Append(tid_t tid);
+
+  PtraceRegistersStatus GetRegistersAndSP(uptr index, uptr *buffer,
+                                          uptr *sp) const;
+  uptr RegisterCount() const;
+
+ private:
+  InternalMmapVector<tid_t> thread_ids_;
+};
+
+// Structure for passing arguments into the tracer thread.
+struct TracerThreadArgument {
+  StopTheWorldCallback callback;
+  void *callback_argument;
+  // The tracer thread waits on this mutex while the parent finishes its
+  // preparations.
+  BlockingMutex mutex;
+  // Tracer thread signals its completion by setting done.
+  atomic_uintptr_t done;
+  uptr parent_pid;
+};
+
+// This class handles thread suspending/unsuspending in the tracer thread.
+class ThreadSuspender {
+ public:
+  explicit ThreadSuspender(pid_t pid, TracerThreadArgument *arg)
+    : arg(arg)
+    , pid_(pid) {
+      CHECK_GE(pid, 0);
+    }
+  bool SuspendAllThreads();
+  void ResumeAllThreads();
+  void KillAllThreads();
+  SuspendedThreadsListLinux &suspended_threads_list() {
+    return suspended_threads_list_;
+  }
+  TracerThreadArgument *arg;
+ private:
+  SuspendedThreadsListLinux suspended_threads_list_;
+  pid_t pid_;
+  bool SuspendThread(tid_t thread_id);
+};
+
+bool ThreadSuspender::SuspendThread(tid_t tid) {
+  // Are we already attached to this thread?
+  // Currently this check takes linear time, however the number of threads is
+  // usually small.
+  if (suspended_threads_list_.ContainsTid(tid)) return false;
+  int pterrno;
+  if (internal_iserror(internal_ptrace(PTRACE_ATTACH, tid, nullptr, nullptr),
+                       &pterrno)) {
+    // Either the thread is dead, or something prevented us from attaching.
+    // Log this event and move on.
+    VReport(1, "Could not attach to thread %zu (errno %d).\n", (uptr)tid,
+            pterrno);
+    return false;
+  } else {
+    VReport(2, "Attached to thread %zu.\n", (uptr)tid);
+    // The thread is not guaranteed to stop before ptrace returns, so we must
+    // wait on it. Note: if the thread receives a signal concurrently,
+    // we can get notification about the signal before notification about stop.
+    // In such case we need to forward the signal to the thread, otherwise
+    // the signal will be missed (as we do PTRACE_DETACH with arg=0) and
+    // any logic relying on signals will break. After forwarding we need to
+    // continue to wait for stopping, because the thread is not stopped yet.
+    // We do ignore delivery of SIGSTOP, because we want to make stop-the-world
+    // as invisible as possible.
+    for (;;) {
+      int status;
+      uptr waitpid_status;
+      HANDLE_EINTR(waitpid_status, internal_waitpid(tid, &status, __WALL));
+      int wperrno;
+      if (internal_iserror(waitpid_status, &wperrno)) {
+        // Got a ECHILD error. I don't think this situation is possible, but it
+        // doesn't hurt to report it.
+        VReport(1, "Waiting on thread %zu failed, detaching (errno %d).\n",
+                (uptr)tid, wperrno);
+        internal_ptrace(PTRACE_DETACH, tid, nullptr, nullptr);
+        return false;
+      }
+      if (WIFSTOPPED(status) && WSTOPSIG(status) != SIGSTOP) {
+        internal_ptrace(PTRACE_CONT, tid, nullptr,
+                        (void*)(uptr)WSTOPSIG(status));
+        continue;
+      }
+      break;
+    }
+    suspended_threads_list_.Append(tid);
+    return true;
+  }
+}
+
+void ThreadSuspender::ResumeAllThreads() {
+  for (uptr i = 0; i < suspended_threads_list_.ThreadCount(); i++) {
+    pid_t tid = suspended_threads_list_.GetThreadID(i);
+    int pterrno;
+    if (!internal_iserror(internal_ptrace(PTRACE_DETACH, tid, nullptr, nullptr),
+                          &pterrno)) {
+      VReport(2, "Detached from thread %d.\n", tid);
+    } else {
+      // Either the thread is dead, or we are already detached.
+      // The latter case is possible, for instance, if this function was called
+      // from a signal handler.
+      VReport(1, "Could not detach from thread %d (errno %d).\n", tid, pterrno);
+    }
+  }
+}
+
+void ThreadSuspender::KillAllThreads() {
+  for (uptr i = 0; i < suspended_threads_list_.ThreadCount(); i++)
+    internal_ptrace(PTRACE_KILL, suspended_threads_list_.GetThreadID(i),
+                    nullptr, nullptr);
+}
+
+bool ThreadSuspender::SuspendAllThreads() {
+  ThreadLister thread_lister(pid_);
+  bool retry = true;
+  InternalMmapVector<tid_t> threads;
+  threads.reserve(128);
+  for (int i = 0; i < 30 && retry; ++i) {
+    retry = false;
+    switch (thread_lister.ListThreads(&threads)) {
+      case ThreadLister::Error:
+        ResumeAllThreads();
+        return false;
+      case ThreadLister::Incomplete:
+        retry = true;
+        break;
+      case ThreadLister::Ok:
+        break;
+    }
+    for (tid_t tid : threads) {
+      if (SuspendThread(tid))
+        retry = true;
+    }
+  }
+  return suspended_threads_list_.ThreadCount();
+}
+
+// Pointer to the ThreadSuspender instance for use in signal handler.
+static ThreadSuspender *thread_suspender_instance = nullptr;
+
+// Synchronous signals that should not be blocked.
+static const int kSyncSignals[] = { SIGABRT, SIGILL, SIGFPE, SIGSEGV, SIGBUS,
+                                    SIGXCPU, SIGXFSZ };
+
+static void TracerThreadDieCallback() {
+  // Generally a call to Die() in the tracer thread should be fatal to the
+  // parent process as well, because they share the address space.
+  // This really only works correctly if all the threads are suspended at this
+  // point. So we correctly handle calls to Die() from within the callback, but
+  // not those that happen before or after the callback. Hopefully there aren't
+  // a lot of opportunities for that to happen...
+  ThreadSuspender *inst = thread_suspender_instance;
+  if (inst && stoptheworld_tracer_pid == internal_getpid()) {
+    inst->KillAllThreads();
+    thread_suspender_instance = nullptr;
+  }
+}
+
+// Signal handler to wake up suspended threads when the tracer thread dies.
+static void TracerThreadSignalHandler(int signum, __sanitizer_siginfo *siginfo,
+                                      void *uctx) {
+  SignalContext ctx(siginfo, uctx);
+  Printf("Tracer caught signal %d: addr=0x%zx pc=0x%zx sp=0x%zx\n", signum,
+         ctx.addr, ctx.pc, ctx.sp);
+  ThreadSuspender *inst = thread_suspender_instance;
+  if (inst) {
+    if (signum == SIGABRT)
+      inst->KillAllThreads();
+    else
+      inst->ResumeAllThreads();
+    RAW_CHECK(RemoveDieCallback(TracerThreadDieCallback));
+    thread_suspender_instance = nullptr;
+    atomic_store(&inst->arg->done, 1, memory_order_relaxed);
+  }
+  internal__exit((signum == SIGABRT) ? 1 : 2);
+}
+
+// Size of alternative stack for signal handlers in the tracer thread.
+static const int kHandlerStackSize = 8192;
+
+// This function will be run as a cloned task.
+static int TracerThread(void* argument) {
+  TracerThreadArgument *tracer_thread_argument =
+      (TracerThreadArgument *)argument;
+
+  internal_prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
+  // Check if parent is already dead.
+  if (internal_getppid() != tracer_thread_argument->parent_pid)
+    internal__exit(4);
+
+  // Wait for the parent thread to finish preparations.
+  tracer_thread_argument->mutex.Lock();
+  tracer_thread_argument->mutex.Unlock();
+
+  RAW_CHECK(AddDieCallback(TracerThreadDieCallback));
+
+  ThreadSuspender thread_suspender(internal_getppid(), tracer_thread_argument);
+  // Global pointer for the signal handler.
+  thread_suspender_instance = &thread_suspender;
+
+  // Alternate stack for signal handling.
+  InternalMmapVector<char> handler_stack_memory(kHandlerStackSize);
+  stack_t handler_stack;
+  internal_memset(&handler_stack, 0, sizeof(handler_stack));
+  handler_stack.ss_sp = handler_stack_memory.data();
+  handler_stack.ss_size = kHandlerStackSize;
+  internal_sigaltstack(&handler_stack, nullptr);
+
+  // Install our handler for synchronous signals. Other signals should be
+  // blocked by the mask we inherited from the parent thread.
+  for (uptr i = 0; i < ARRAY_SIZE(kSyncSignals); i++) {
+    __sanitizer_sigaction act;
+    internal_memset(&act, 0, sizeof(act));
+    act.sigaction = TracerThreadSignalHandler;
+    act.sa_flags = SA_ONSTACK | SA_SIGINFO;
+    internal_sigaction_norestorer(kSyncSignals[i], &act, 0);
+  }
+
+  int exit_code = 0;
+  if (!thread_suspender.SuspendAllThreads()) {
+    VReport(1, "Failed suspending threads.\n");
+    exit_code = 3;
+  } else {
+    tracer_thread_argument->callback(thread_suspender.suspended_threads_list(),
+                                     tracer_thread_argument->callback_argument);
+    thread_suspender.ResumeAllThreads();
+    exit_code = 0;
+  }
+  RAW_CHECK(RemoveDieCallback(TracerThreadDieCallback));
+  thread_suspender_instance = nullptr;
+  atomic_store(&tracer_thread_argument->done, 1, memory_order_relaxed);
+  return exit_code;
+}
+
+class ScopedStackSpaceWithGuard {
+ public:
+  explicit ScopedStackSpaceWithGuard(uptr stack_size) {
+    stack_size_ = stack_size;
+    guard_size_ = GetPageSizeCached();
+    // FIXME: Omitting MAP_STACK here works in current kernels but might break
+    // in the future.
+    guard_start_ = (uptr)MmapOrDie(stack_size_ + guard_size_,
+                                   "ScopedStackWithGuard");
+    CHECK(MprotectNoAccess((uptr)guard_start_, guard_size_));
+  }
+  ~ScopedStackSpaceWithGuard() {
+    UnmapOrDie((void *)guard_start_, stack_size_ + guard_size_);
+  }
+  void *Bottom() const {
+    return (void *)(guard_start_ + stack_size_ + guard_size_);
+  }
+
+ private:
+  uptr stack_size_;
+  uptr guard_size_;
+  uptr guard_start_;
+};
+
+// We have a limitation on the stack frame size, so some stuff had to be moved
+// into globals.
+static __sanitizer_sigset_t blocked_sigset;
+static __sanitizer_sigset_t old_sigset;
+
+class StopTheWorldScope {
+ public:
+  StopTheWorldScope() {
+    // Make this process dumpable. Processes that are not dumpable cannot be
+    // attached to.
+    process_was_dumpable_ = internal_prctl(PR_GET_DUMPABLE, 0, 0, 0, 0);
+    if (!process_was_dumpable_)
+      internal_prctl(PR_SET_DUMPABLE, 1, 0, 0, 0);
+  }
+
+  ~StopTheWorldScope() {
+    // Restore the dumpable flag.
+    if (!process_was_dumpable_)
+      internal_prctl(PR_SET_DUMPABLE, 0, 0, 0, 0);
+  }
+
+ private:
+  int process_was_dumpable_;
+};
+
+// When sanitizer output is being redirected to file (i.e. by using log_path),
+// the tracer should write to the parent's log instead of trying to open a new
+// file. Alert the logging code to the fact that we have a tracer.
+struct ScopedSetTracerPID {
+  explicit ScopedSetTracerPID(uptr tracer_pid) {
+    stoptheworld_tracer_pid = tracer_pid;
+    stoptheworld_tracer_ppid = internal_getpid();
+  }
+  ~ScopedSetTracerPID() {
+    stoptheworld_tracer_pid = 0;
+    stoptheworld_tracer_ppid = 0;
+  }
+};
+
+void StopTheWorld(StopTheWorldCallback callback, void *argument) {
+  StopTheWorldScope in_stoptheworld;
+  // Prepare the arguments for TracerThread.
+  struct TracerThreadArgument tracer_thread_argument;
+  tracer_thread_argument.callback = callback;
+  tracer_thread_argument.callback_argument = argument;
+  tracer_thread_argument.parent_pid = internal_getpid();
+  atomic_store(&tracer_thread_argument.done, 0, memory_order_relaxed);
+  const uptr kTracerStackSize = 2 * 1024 * 1024;
+  ScopedStackSpaceWithGuard tracer_stack(kTracerStackSize);
+  // Block the execution of TracerThread until after we have set ptrace
+  // permissions.
+  tracer_thread_argument.mutex.Lock();
+  // Signal handling story.
+  // We don't want async signals to be delivered to the tracer thread,
+  // so we block all async signals before creating the thread. An async signal
+  // handler can temporary modify errno, which is shared with this thread.
+  // We ought to use pthread_sigmask here, because sigprocmask has undefined
+  // behavior in multithreaded programs. However, on linux sigprocmask is
+  // equivalent to pthread_sigmask with the exception that pthread_sigmask
+  // does not allow to block some signals used internally in pthread
+  // implementation. We are fine with blocking them here, we are really not
+  // going to pthread_cancel the thread.
+  // The tracer thread should not raise any synchronous signals. But in case it
+  // does, we setup a special handler for sync signals that properly kills the
+  // parent as well. Note: we don't pass CLONE_SIGHAND to clone, so handlers
+  // in the tracer thread won't interfere with user program. Double note: if a
+  // user does something along the lines of 'kill -11 pid', that can kill the
+  // process even if user setup own handler for SEGV.
+  // Thing to watch out for: this code should not change behavior of user code
+  // in any observable way. In particular it should not override user signal
+  // handlers.
+  internal_sigfillset(&blocked_sigset);
+  for (uptr i = 0; i < ARRAY_SIZE(kSyncSignals); i++)
+    internal_sigdelset(&blocked_sigset, kSyncSignals[i]);
+  int rv = internal_sigprocmask(SIG_BLOCK, &blocked_sigset, &old_sigset);
+  CHECK_EQ(rv, 0);
+  uptr tracer_pid = internal_clone(
+      TracerThread, tracer_stack.Bottom(),
+      CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_UNTRACED,
+      &tracer_thread_argument, nullptr /* parent_tidptr */,
+      nullptr /* newtls */, nullptr /* child_tidptr */);
+  internal_sigprocmask(SIG_SETMASK, &old_sigset, 0);
+  int local_errno = 0;
+  if (internal_iserror(tracer_pid, &local_errno)) {
+    VReport(1, "Failed spawning a tracer thread (errno %d).\n", local_errno);
+    tracer_thread_argument.mutex.Unlock();
+  } else {
+    ScopedSetTracerPID scoped_set_tracer_pid(tracer_pid);
+    // On some systems we have to explicitly declare that we want to be traced
+    // by the tracer thread.
+    internal_prctl(PR_SET_PTRACER, tracer_pid, 0, 0, 0);
+    // Allow the tracer thread to start.
+    tracer_thread_argument.mutex.Unlock();
+    // NOTE: errno is shared between this thread and the tracer thread.
+    // internal_waitpid() may call syscall() which can access/spoil errno,
+    // so we can't call it now. Instead we for the tracer thread to finish using
+    // the spin loop below. Man page for sched_yield() says "In the Linux
+    // implementation, sched_yield() always succeeds", so let's hope it does not
+    // spoil errno. Note that this spin loop runs only for brief periods before
+    // the tracer thread has suspended us and when it starts unblocking threads.
+    while (atomic_load(&tracer_thread_argument.done, memory_order_relaxed) == 0)
+      sched_yield();
+    // Now the tracer thread is about to exit and does not touch errno,
+    // wait for it.
+    for (;;) {
+      uptr waitpid_status = internal_waitpid(tracer_pid, nullptr, __WALL);
+      if (!internal_iserror(waitpid_status, &local_errno))
+        break;
+      if (local_errno == EINTR)
+        continue;
+      VReport(1, "Waiting on the tracer thread failed (errno %d).\n",
+              local_errno);
+      break;
+    }
+  }
+}
+
+// Platform-specific methods from SuspendedThreadsList.
+#if SANITIZER_ANDROID && defined(__arm__)
+typedef pt_regs regs_struct;
+#define REG_SP ARM_sp
+
+#elif SANITIZER_LINUX && defined(__arm__)
+typedef user_regs regs_struct;
+#define REG_SP uregs[13]
+
+#elif defined(__i386__) || defined(__x86_64__)
+typedef user_regs_struct regs_struct;
+#if defined(__i386__)
+#define REG_SP esp
+#else
+#define REG_SP rsp
+#endif
+
+#elif defined(__powerpc__) || defined(__powerpc64__)
+typedef pt_regs regs_struct;
+#define REG_SP gpr[PT_R1]
+
+#elif defined(__mips__)
+typedef struct user regs_struct;
+# if SANITIZER_ANDROID
+#  define REG_SP regs[EF_R29]
+# else
+#  define REG_SP regs[EF_REG29]
+# endif
+
+#elif defined(__aarch64__)
+typedef struct user_pt_regs regs_struct;
+#define REG_SP sp
+#define ARCH_IOVEC_FOR_GETREGSET
+
+#elif defined(__s390__)
+typedef _user_regs_struct regs_struct;
+#define REG_SP gprs[15]
+#define ARCH_IOVEC_FOR_GETREGSET
+
+#else
+#error "Unsupported architecture"
+#endif // SANITIZER_ANDROID && defined(__arm__)
+
+tid_t SuspendedThreadsListLinux::GetThreadID(uptr index) const {
+  CHECK_LT(index, thread_ids_.size());
+  return thread_ids_[index];
+}
+
+uptr SuspendedThreadsListLinux::ThreadCount() const {
+  return thread_ids_.size();
+}
+
+bool SuspendedThreadsListLinux::ContainsTid(tid_t thread_id) const {
+  for (uptr i = 0; i < thread_ids_.size(); i++) {
+    if (thread_ids_[i] == thread_id) return true;
+  }
+  return false;
+}
+
+void SuspendedThreadsListLinux::Append(tid_t tid) {
+  thread_ids_.push_back(tid);
+}
+
+PtraceRegistersStatus SuspendedThreadsListLinux::GetRegistersAndSP(
+    uptr index, uptr *buffer, uptr *sp) const {
+  pid_t tid = GetThreadID(index);
+  regs_struct regs;
+  int pterrno;
+#ifdef ARCH_IOVEC_FOR_GETREGSET
+  struct iovec regset_io;
+  regset_io.iov_base = &regs;
+  regset_io.iov_len = sizeof(regs_struct);
+  bool isErr = internal_iserror(internal_ptrace(PTRACE_GETREGSET, tid,
+                                (void*)NT_PRSTATUS, (void*)&regset_io),
+                                &pterrno);
+#else
+  bool isErr = internal_iserror(internal_ptrace(PTRACE_GETREGS, tid, nullptr,
+                                &regs), &pterrno);
+#endif
+  if (isErr) {
+    VReport(1, "Could not get registers from thread %d (errno %d).\n", tid,
+            pterrno);
+    // ESRCH means that the given thread is not suspended or already dead.
+    // Therefore it's unsafe to inspect its data (e.g. walk through stack) and
+    // we should notify caller about this.
+    return pterrno == ESRCH ? REGISTERS_UNAVAILABLE_FATAL
+                            : REGISTERS_UNAVAILABLE;
+  }
+
+  *sp = regs.REG_SP;
+  internal_memcpy(buffer, &regs, sizeof(regs));
+  return REGISTERS_AVAILABLE;
+}
+
+uptr SuspendedThreadsListLinux::RegisterCount() const {
+  return sizeof(regs_struct) / sizeof(uptr);
+}
+} // namespace __sanitizer
+
+#endif  // SANITIZER_LINUX && (defined(__x86_64__) || defined(__mips__)
+        // || defined(__aarch64__) || defined(__powerpc64__)
+        // || defined(__s390__) || defined(__i386__) || defined(__arm__)
diff --git a/lib/tsan/sanitizer_common/sanitizer_stoptheworld_netbsd_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_stoptheworld_netbsd_libcdep.cpp
new file mode 100644
index 0000000000..1ed2134325
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_stoptheworld_netbsd_libcdep.cpp
@@ -0,0 +1,364 @@
+//===-- sanitizer_stoptheworld_netbsd_libcdep.cpp -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// See sanitizer_stoptheworld.h for details.
+// This implementation was inspired by Markus Gutschke's linuxthreads.cc.
+//
+// This is a NetBSD variation of Linux stoptheworld implementation
+// See sanitizer_stoptheworld_linux_libcdep.cpp for code comments.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#if SANITIZER_NETBSD
+
+#include "sanitizer_stoptheworld.h"
+
+#include "sanitizer_atomic.h"
+#include "sanitizer_platform_limits_posix.h"
+
+#include <sys/types.h>
+
+#include <sys/ptrace.h>
+#include <sys/uio.h>
+#include <sys/wait.h>
+
+#include <machine/reg.h>
+
+#include <elf.h>
+#include <errno.h>
+#include <sched.h>
+#include <signal.h>
+#include <stddef.h>
+
+#define internal_sigaction_norestorer internal_sigaction
+
+#include "sanitizer_common.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_libc.h"
+#include "sanitizer_linux.h"
+#include "sanitizer_mutex.h"
+#include "sanitizer_placement_new.h"
+
+namespace __sanitizer {
+
+class SuspendedThreadsListNetBSD : public SuspendedThreadsList {
+ public:
+  SuspendedThreadsListNetBSD() { thread_ids_.reserve(1024); }
+
+  tid_t GetThreadID(uptr index) const;
+  uptr ThreadCount() const;
+  bool ContainsTid(tid_t thread_id) const;
+  void Append(tid_t tid);
+
+  PtraceRegistersStatus GetRegistersAndSP(uptr index, uptr *buffer,
+                                          uptr *sp) const;
+  uptr RegisterCount() const;
+
+ private:
+  InternalMmapVector<tid_t> thread_ids_;
+};
+
+struct TracerThreadArgument {
+  StopTheWorldCallback callback;
+  void *callback_argument;
+  BlockingMutex mutex;
+  atomic_uintptr_t done;
+  uptr parent_pid;
+};
+
+class ThreadSuspender {
+ public:
+  explicit ThreadSuspender(pid_t pid, TracerThreadArgument *arg)
+      : arg(arg), pid_(pid) {
+    CHECK_GE(pid, 0);
+  }
+  bool SuspendAllThreads();
+  void ResumeAllThreads();
+  void KillAllThreads();
+  SuspendedThreadsListNetBSD &suspended_threads_list() {
+    return suspended_threads_list_;
+  }
+  TracerThreadArgument *arg;
+
+ private:
+  SuspendedThreadsListNetBSD suspended_threads_list_;
+  pid_t pid_;
+};
+
+void ThreadSuspender::ResumeAllThreads() {
+  int pterrno;
+  if (!internal_iserror(internal_ptrace(PT_DETACH, pid_, (void *)(uptr)1, 0),
+                        &pterrno)) {
+    VReport(2, "Detached from process %d.\n", pid_);
+  } else {
+    VReport(1, "Could not detach from process %d (errno %d).\n", pid_, pterrno);
+  }
+}
+
+void ThreadSuspender::KillAllThreads() {
+  internal_ptrace(PT_KILL, pid_, nullptr, 0);
+}
+
+bool ThreadSuspender::SuspendAllThreads() {
+  int pterrno;
+  if (internal_iserror(internal_ptrace(PT_ATTACH, pid_, nullptr, 0),
+                       &pterrno)) {
+    Printf("Could not attach to process %d (errno %d).\n", pid_, pterrno);
+    return false;
+  }
+
+  int status;
+  uptr waitpid_status;
+  HANDLE_EINTR(waitpid_status, internal_waitpid(pid_, &status, 0));
+
+  VReport(2, "Attached to process %d.\n", pid_);
+
+#ifdef PT_LWPNEXT
+  struct ptrace_lwpstatus pl;
+  int op = PT_LWPNEXT;
+#else
+  struct ptrace_lwpinfo pl;
+  int op = PT_LWPINFO;
+#endif
+
+  pl.pl_lwpid = 0;
+
+  int val;
+  while ((val = ptrace(op, pid_, (void *)&pl, sizeof(pl))) != -1 &&
+         pl.pl_lwpid != 0) {
+    suspended_threads_list_.Append(pl.pl_lwpid);
+    VReport(2, "Appended thread %d in process %d.\n", pl.pl_lwpid, pid_);
+  }
+  return true;
+}
+
+// Pointer to the ThreadSuspender instance for use in signal handler.
+static ThreadSuspender *thread_suspender_instance = nullptr;
+
+// Synchronous signals that should not be blocked.
+static const int kSyncSignals[] = {SIGABRT, SIGILL,  SIGFPE, SIGSEGV,
+                                   SIGBUS,  SIGXCPU, SIGXFSZ};
+
+static void TracerThreadDieCallback() {
+  ThreadSuspender *inst = thread_suspender_instance;
+  if (inst && stoptheworld_tracer_pid == internal_getpid()) {
+    inst->KillAllThreads();
+    thread_suspender_instance = nullptr;
+  }
+}
+
+// Signal handler to wake up suspended threads when the tracer thread dies.
+static void TracerThreadSignalHandler(int signum, __sanitizer_siginfo *siginfo,
+                                      void *uctx) {
+  SignalContext ctx(siginfo, uctx);
+  Printf("Tracer caught signal %d: addr=0x%zx pc=0x%zx sp=0x%zx\n", signum,
+         ctx.addr, ctx.pc, ctx.sp);
+  ThreadSuspender *inst = thread_suspender_instance;
+  if (inst) {
+    if (signum == SIGABRT)
+      inst->KillAllThreads();
+    else
+      inst->ResumeAllThreads();
+    RAW_CHECK(RemoveDieCallback(TracerThreadDieCallback));
+    thread_suspender_instance = nullptr;
+    atomic_store(&inst->arg->done, 1, memory_order_relaxed);
+  }
+  internal__exit((signum == SIGABRT) ? 1 : 2);
+}
+
+// Size of alternative stack for signal handlers in the tracer thread.
+static const int kHandlerStackSize = 8192;
+
+// This function will be run as a cloned task.
+static int TracerThread(void *argument) {
+  TracerThreadArgument *tracer_thread_argument =
+      (TracerThreadArgument *)argument;
+
+  // Check if parent is already dead.
+  if (internal_getppid() != tracer_thread_argument->parent_pid)
+    internal__exit(4);
+
+  // Wait for the parent thread to finish preparations.
+  tracer_thread_argument->mutex.Lock();
+  tracer_thread_argument->mutex.Unlock();
+
+  RAW_CHECK(AddDieCallback(TracerThreadDieCallback));
+
+  ThreadSuspender thread_suspender(internal_getppid(), tracer_thread_argument);
+  // Global pointer for the signal handler.
+  thread_suspender_instance = &thread_suspender;
+
+  // Alternate stack for signal handling.
+  InternalMmapVector<char> handler_stack_memory(kHandlerStackSize);
+  stack_t handler_stack;
+  internal_memset(&handler_stack, 0, sizeof(handler_stack));
+  handler_stack.ss_sp = handler_stack_memory.data();
+  handler_stack.ss_size = kHandlerStackSize;
+  internal_sigaltstack(&handler_stack, nullptr);
+
+  // Install our handler for synchronous signals. Other signals should be
+  // blocked by the mask we inherited from the parent thread.
+  for (uptr i = 0; i < ARRAY_SIZE(kSyncSignals); i++) {
+    __sanitizer_sigaction act;
+    internal_memset(&act, 0, sizeof(act));
+    act.sigaction = TracerThreadSignalHandler;
+    act.sa_flags = SA_ONSTACK | SA_SIGINFO;
+    internal_sigaction_norestorer(kSyncSignals[i], &act, 0);
+  }
+
+  int exit_code = 0;
+  if (!thread_suspender.SuspendAllThreads()) {
+    VReport(1, "Failed suspending threads.\n");
+    exit_code = 3;
+  } else {
+    tracer_thread_argument->callback(thread_suspender.suspended_threads_list(),
+                                     tracer_thread_argument->callback_argument);
+    thread_suspender.ResumeAllThreads();
+    exit_code = 0;
+  }
+  RAW_CHECK(RemoveDieCallback(TracerThreadDieCallback));
+  thread_suspender_instance = nullptr;
+  atomic_store(&tracer_thread_argument->done, 1, memory_order_relaxed);
+  return exit_code;
+}
+
+class ScopedStackSpaceWithGuard {
+ public:
+  explicit ScopedStackSpaceWithGuard(uptr stack_size) {
+    stack_size_ = stack_size;
+    guard_size_ = GetPageSizeCached();
+    // FIXME: Omitting MAP_STACK here works in current kernels but might break
+    // in the future.
+    guard_start_ =
+        (uptr)MmapOrDie(stack_size_ + guard_size_, "ScopedStackWithGuard");
+    CHECK(MprotectNoAccess((uptr)guard_start_, guard_size_));
+  }
+  ~ScopedStackSpaceWithGuard() {
+    UnmapOrDie((void *)guard_start_, stack_size_ + guard_size_);
+  }
+  void *Bottom() const {
+    return (void *)(guard_start_ + stack_size_ + guard_size_);
+  }
+
+ private:
+  uptr stack_size_;
+  uptr guard_size_;
+  uptr guard_start_;
+};
+
+static __sanitizer_sigset_t blocked_sigset;
+static __sanitizer_sigset_t old_sigset;
+
+struct ScopedSetTracerPID {
+  explicit ScopedSetTracerPID(uptr tracer_pid) {
+    stoptheworld_tracer_pid = tracer_pid;
+    stoptheworld_tracer_ppid = internal_getpid();
+  }
+  ~ScopedSetTracerPID() {
+    stoptheworld_tracer_pid = 0;
+    stoptheworld_tracer_ppid = 0;
+  }
+};
+
+void StopTheWorld(StopTheWorldCallback callback, void *argument) {
+  // Prepare the arguments for TracerThread.
+  struct TracerThreadArgument tracer_thread_argument;
+  tracer_thread_argument.callback = callback;
+  tracer_thread_argument.callback_argument = argument;
+  tracer_thread_argument.parent_pid = internal_getpid();
+  atomic_store(&tracer_thread_argument.done, 0, memory_order_relaxed);
+  const uptr kTracerStackSize = 2 * 1024 * 1024;
+  ScopedStackSpaceWithGuard tracer_stack(kTracerStackSize);
+
+  tracer_thread_argument.mutex.Lock();
+
+  internal_sigfillset(&blocked_sigset);
+  for (uptr i = 0; i < ARRAY_SIZE(kSyncSignals); i++)
+    internal_sigdelset(&blocked_sigset, kSyncSignals[i]);
+  int rv = internal_sigprocmask(SIG_BLOCK, &blocked_sigset, &old_sigset);
+  CHECK_EQ(rv, 0);
+  uptr tracer_pid = internal_clone(TracerThread, tracer_stack.Bottom(),
+                                   CLONE_VM | CLONE_FS | CLONE_FILES,
+                                   &tracer_thread_argument);
+  internal_sigprocmask(SIG_SETMASK, &old_sigset, 0);
+  int local_errno = 0;
+  if (internal_iserror(tracer_pid, &local_errno)) {
+    VReport(1, "Failed spawning a tracer thread (errno %d).\n", local_errno);
+    tracer_thread_argument.mutex.Unlock();
+  } else {
+    ScopedSetTracerPID scoped_set_tracer_pid(tracer_pid);
+
+    tracer_thread_argument.mutex.Unlock();
+
+    while (atomic_load(&tracer_thread_argument.done, memory_order_relaxed) == 0)
+      sched_yield();
+
+    for (;;) {
+      uptr waitpid_status = internal_waitpid(tracer_pid, nullptr, __WALL);
+      if (!internal_iserror(waitpid_status, &local_errno))
+        break;
+      if (local_errno == EINTR)
+        continue;
+      VReport(1, "Waiting on the tracer thread failed (errno %d).\n",
+              local_errno);
+      break;
+    }
+  }
+}
+
+tid_t SuspendedThreadsListNetBSD::GetThreadID(uptr index) const {
+  CHECK_LT(index, thread_ids_.size());
+  return thread_ids_[index];
+}
+
+uptr SuspendedThreadsListNetBSD::ThreadCount() const {
+  return thread_ids_.size();
+}
+
+bool SuspendedThreadsListNetBSD::ContainsTid(tid_t thread_id) const {
+  for (uptr i = 0; i < thread_ids_.size(); i++) {
+    if (thread_ids_[i] == thread_id)
+      return true;
+  }
+  return false;
+}
+
+void SuspendedThreadsListNetBSD::Append(tid_t tid) {
+  thread_ids_.push_back(tid);
+}
+
+PtraceRegistersStatus SuspendedThreadsListNetBSD::GetRegistersAndSP(
+    uptr index, uptr *buffer, uptr *sp) const {
+  lwpid_t tid = GetThreadID(index);
+  pid_t ppid = internal_getppid();
+  struct reg regs;
+  int pterrno;
+  bool isErr =
+      internal_iserror(internal_ptrace(PT_GETREGS, ppid, &regs, tid), &pterrno);
+  if (isErr) {
+    VReport(1,
+            "Could not get registers from process %d thread %d (errno %d).\n",
+            ppid, tid, pterrno);
+    return pterrno == ESRCH ? REGISTERS_UNAVAILABLE_FATAL
+                            : REGISTERS_UNAVAILABLE;
+  }
+
+  *sp = PTRACE_REG_SP(&regs);
+  internal_memcpy(buffer, &regs, sizeof(regs));
+
+  return REGISTERS_AVAILABLE;
+}
+
+uptr SuspendedThreadsListNetBSD::RegisterCount() const {
+  return sizeof(struct reg) / sizeof(uptr);
+}
+}  // namespace __sanitizer
+
+#endif
diff --git a/lib/tsan/sanitizer_common/sanitizer_symbolizer.cpp b/lib/tsan/sanitizer_common/sanitizer_symbolizer.cpp
new file mode 100644
index 0000000000..0c4b84c767
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_symbolizer.cpp
@@ -0,0 +1,135 @@
+//===-- sanitizer_symbolizer.cpp ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_allocator_internal.h"
+#include "sanitizer_platform.h"
+#include "sanitizer_internal_defs.h"
+#include "sanitizer_libc.h"
+#include "sanitizer_placement_new.h"
+#include "sanitizer_symbolizer_internal.h"
+
+namespace __sanitizer {
+
+AddressInfo::AddressInfo() {
+  internal_memset(this, 0, sizeof(AddressInfo));
+  function_offset = kUnknown;
+}
+
+void AddressInfo::Clear() {
+  InternalFree(module);
+  InternalFree(function);
+  InternalFree(file);
+  internal_memset(this, 0, sizeof(AddressInfo));
+  function_offset = kUnknown;
+}
+
+void AddressInfo::FillModuleInfo(const char *mod_name, uptr mod_offset,
+                                 ModuleArch mod_arch) {
+  module = internal_strdup(mod_name);
+  module_offset = mod_offset;
+  module_arch = mod_arch;
+}
+
+SymbolizedStack::SymbolizedStack() : next(nullptr), info() {}
+
+SymbolizedStack *SymbolizedStack::New(uptr addr) {
+  void *mem = InternalAlloc(sizeof(SymbolizedStack));
+  SymbolizedStack *res = new(mem) SymbolizedStack();
+  res->info.address = addr;
+  return res;
+}
+
+void SymbolizedStack::ClearAll() {
+  info.Clear();
+  if (next)
+    next->ClearAll();
+  InternalFree(this);
+}
+
+DataInfo::DataInfo() {
+  internal_memset(this, 0, sizeof(DataInfo));
+}
+
+void DataInfo::Clear() {
+  InternalFree(module);
+  InternalFree(file);
+  InternalFree(name);
+  internal_memset(this, 0, sizeof(DataInfo));
+}
+
+void FrameInfo::Clear() {
+  InternalFree(module);
+  for (LocalInfo &local : locals) {
+    InternalFree(local.function_name);
+    InternalFree(local.name);
+    InternalFree(local.decl_file);
+  }
+  locals.clear();
+}
+
+Symbolizer *Symbolizer::symbolizer_;
+StaticSpinMutex Symbolizer::init_mu_;
+LowLevelAllocator Symbolizer::symbolizer_allocator_;
+
+void Symbolizer::InvalidateModuleList() {
+  modules_fresh_ = false;
+}
+
+void Symbolizer::AddHooks(Symbolizer::StartSymbolizationHook start_hook,
+                          Symbolizer::EndSymbolizationHook end_hook) {
+  CHECK(start_hook_ == 0 && end_hook_ == 0);
+  start_hook_ = start_hook;
+  end_hook_ = end_hook;
+}
+
+const char *Symbolizer::ModuleNameOwner::GetOwnedCopy(const char *str) {
+  mu_->CheckLocked();
+
+  // 'str' will be the same string multiple times in a row, optimize this case.
+  if (last_match_ && !internal_strcmp(last_match_, str))
+    return last_match_;
+
+  // FIXME: this is linear search.
+  // We should optimize this further if this turns out to be a bottleneck later.
+  for (uptr i = 0; i < storage_.size(); ++i) {
+    if (!internal_strcmp(storage_[i], str)) {
+      last_match_ = storage_[i];
+      return last_match_;
+    }
+  }
+  last_match_ = internal_strdup(str);
+  storage_.push_back(last_match_);
+  return last_match_;
+}
+
+Symbolizer::Symbolizer(IntrusiveList<SymbolizerTool> tools)
+    : module_names_(&mu_), modules_(), modules_fresh_(false), tools_(tools),
+      start_hook_(0), end_hook_(0) {}
+
+Symbolizer::SymbolizerScope::SymbolizerScope(const Symbolizer *sym)
+    : sym_(sym) {
+  if (sym_->start_hook_)
+    sym_->start_hook_();
+}
+
+Symbolizer::SymbolizerScope::~SymbolizerScope() {
+  if (sym_->end_hook_)
+    sym_->end_hook_();
+}
+
+void Symbolizer::LateInitializeTools() {
+  for (auto &tool : tools_) {
+    tool.LateInitialize();
+  }
+}
+
+}  // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_symbolizer_libbacktrace.cpp b/lib/tsan/sanitizer_common/sanitizer_symbolizer_libbacktrace.cpp
new file mode 100644
index 0000000000..27ed222745
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_symbolizer_libbacktrace.cpp
@@ -0,0 +1,209 @@
+//===-- sanitizer_symbolizer_libbacktrace.cpp -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+// Libbacktrace implementation of symbolizer parts.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#include "sanitizer_internal_defs.h"
+#include "sanitizer_symbolizer.h"
+#include "sanitizer_symbolizer_libbacktrace.h"
+
+#if SANITIZER_LIBBACKTRACE
+# include "backtrace-supported.h"
+# if SANITIZER_POSIX && BACKTRACE_SUPPORTED && !BACKTRACE_USES_MALLOC
+#  include "backtrace.h"
+#  if SANITIZER_CP_DEMANGLE
+#   undef ARRAY_SIZE
+#   include "demangle.h"
+#  endif
+# else
+#  define SANITIZER_LIBBACKTRACE 0
+# endif
+#endif
+
+namespace __sanitizer {
+
+static char *DemangleAlloc(const char *name, bool always_alloc);
+
+#if SANITIZER_LIBBACKTRACE
+
+namespace {
+
+# if SANITIZER_CP_DEMANGLE
+struct CplusV3DemangleData {
+  char *buf;
+  uptr size, allocated;
+};
+
+extern "C" {
+static void CplusV3DemangleCallback(const char *s, size_t l, void *vdata) {
+  CplusV3DemangleData *data = (CplusV3DemangleData *)vdata;
+  uptr needed = data->size + l + 1;
+  if (needed > data->allocated) {
+    data->allocated *= 2;
+    if (needed > data->allocated)
+      data->allocated = needed;
+    char *buf = (char *)InternalAlloc(data->allocated);
+    if (data->buf) {
+      internal_memcpy(buf, data->buf, data->size);
+      InternalFree(data->buf);
+    }
+    data->buf = buf;
+  }
+  internal_memcpy(data->buf + data->size, s, l);
+  data->buf[data->size + l] = '\0';
+  data->size += l;
+}
+}  // extern "C"
+
+char *CplusV3Demangle(const char *name) {
+  CplusV3DemangleData data;
+  data.buf = 0;
+  data.size = 0;
+  data.allocated = 0;
+  if (cplus_demangle_v3_callback(name, DMGL_PARAMS | DMGL_ANSI,
+                                 CplusV3DemangleCallback, &data)) {
+    if (data.size + 64 > data.allocated)
+      return data.buf;
+    char *buf = internal_strdup(data.buf);
+    InternalFree(data.buf);
+    return buf;
+  }
+  if (data.buf)
+    InternalFree(data.buf);
+  return 0;
+}
+# endif  // SANITIZER_CP_DEMANGLE
+
+struct SymbolizeCodeCallbackArg {
+  SymbolizedStack *first;
+  SymbolizedStack *last;
+  uptr frames_symbolized;
+
+  AddressInfo *get_new_frame(uintptr_t addr) {
+    CHECK(last);
+    if (frames_symbolized > 0) {
+      SymbolizedStack *cur = SymbolizedStack::New(addr);
+      AddressInfo *info = &cur->info;
+      info->FillModuleInfo(first->info.module, first->info.module_offset,
+                           first->info.module_arch);
+      last->next = cur;
+      last = cur;
+    }
+    CHECK_EQ(addr, first->info.address);
+    CHECK_EQ(addr, last->info.address);
+    return &last->info;
+  }
+};
+
+extern "C" {
+static int SymbolizeCodePCInfoCallback(void *vdata, uintptr_t addr,
+                                       const char *filename, int lineno,
+                                       const char *function) {
+  SymbolizeCodeCallbackArg *cdata = (SymbolizeCodeCallbackArg *)vdata;
+  if (function) {
+    AddressInfo *info = cdata->get_new_frame(addr);
+    info->function = DemangleAlloc(function, /*always_alloc*/ true);
+    if (filename)
+      info->file = internal_strdup(filename);
+    info->line = lineno;
+    cdata->frames_symbolized++;
+  }
+  return 0;
+}
+
+static void SymbolizeCodeCallback(void *vdata, uintptr_t addr,
+                                  const char *symname, uintptr_t, uintptr_t) {
+  SymbolizeCodeCallbackArg *cdata = (SymbolizeCodeCallbackArg *)vdata;
+  if (symname) {
+    AddressInfo *info = cdata->get_new_frame(addr);
+    info->function = DemangleAlloc(symname, /*always_alloc*/ true);
+    cdata->frames_symbolized++;
+  }
+}
+
+static void SymbolizeDataCallback(void *vdata, uintptr_t, const char *symname,
+                                  uintptr_t symval, uintptr_t symsize) {
+  DataInfo *info = (DataInfo *)vdata;
+  if (symname && symval) {
+    info->name = DemangleAlloc(symname, /*always_alloc*/ true);
+    info->start = symval;
+    info->size = symsize;
+  }
+}
+
+static void ErrorCallback(void *, const char *, int) {}
+}  // extern "C"
+
+}  // namespace
+
+LibbacktraceSymbolizer *LibbacktraceSymbolizer::get(LowLevelAllocator *alloc) {
+  // State created in backtrace_create_state is leaked.
+  void *state = (void *)(backtrace_create_state("/proc/self/exe", 0,
+                                                ErrorCallback, NULL));
+  if (!state)
+    return 0;
+  return new(*alloc) LibbacktraceSymbolizer(state);
+}
+
+bool LibbacktraceSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
+  SymbolizeCodeCallbackArg data;
+  data.first = stack;
+  data.last = stack;
+  data.frames_symbolized = 0;
+  backtrace_pcinfo((backtrace_state *)state_, addr, SymbolizeCodePCInfoCallback,
+                   ErrorCallback, &data);
+  if (data.frames_symbolized > 0)
+    return true;
+  backtrace_syminfo((backtrace_state *)state_, addr, SymbolizeCodeCallback,
+                    ErrorCallback, &data);
+  return (data.frames_symbolized > 0);
+}
+
+bool LibbacktraceSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
+  backtrace_syminfo((backtrace_state *)state_, addr, SymbolizeDataCallback,
+                    ErrorCallback, info);
+  return true;
+}
+
+#else  // SANITIZER_LIBBACKTRACE
+
+LibbacktraceSymbolizer *LibbacktraceSymbolizer::get(LowLevelAllocator *alloc) {
+  return 0;
+}
+
+bool LibbacktraceSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
+  (void)state_;
+  return false;
+}
+
+bool LibbacktraceSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
+  return false;
+}
+
+#endif  // SANITIZER_LIBBACKTRACE
+
+static char *DemangleAlloc(const char *name, bool always_alloc) {
+#if SANITIZER_LIBBACKTRACE && SANITIZER_CP_DEMANGLE
+  if (char *demangled = CplusV3Demangle(name))
+    return demangled;
+#endif
+  if (always_alloc)
+    return internal_strdup(name);
+  return 0;
+}
+
+const char *LibbacktraceSymbolizer::Demangle(const char *name) {
+  return DemangleAlloc(name, /*always_alloc*/ false);
+}
+
+}  // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_symbolizer_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_symbolizer_libcdep.cpp
new file mode 100644
index 0000000000..490c6fe89b
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_symbolizer_libcdep.cpp
@@ -0,0 +1,554 @@
+//===-- sanitizer_symbolizer_libcdep.cpp ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_allocator_internal.h"
+#include "sanitizer_internal_defs.h"
+#include "sanitizer_symbolizer_internal.h"
+
+namespace __sanitizer {
+
+Symbolizer *Symbolizer::GetOrInit() {
+  SpinMutexLock l(&init_mu_);
+  if (symbolizer_)
+    return symbolizer_;
+  symbolizer_ = PlatformInit();
+  CHECK(symbolizer_);
+  return symbolizer_;
+}
+
+// See sanitizer_symbolizer_markup.cpp.
+#if !SANITIZER_SYMBOLIZER_MARKUP
+
+const char *ExtractToken(const char *str, const char *delims, char **result) {
+  uptr prefix_len = internal_strcspn(str, delims);
+  *result = (char*)InternalAlloc(prefix_len + 1);
+  internal_memcpy(*result, str, prefix_len);
+  (*result)[prefix_len] = '\0';
+  const char *prefix_end = str + prefix_len;
+  if (*prefix_end != '\0') prefix_end++;
+  return prefix_end;
+}
+
+const char *ExtractInt(const char *str, const char *delims, int *result) {
+  char *buff = nullptr;
+  const char *ret = ExtractToken(str, delims, &buff);
+  if (buff) {
+    *result = (int)internal_atoll(buff);
+  }
+  InternalFree(buff);
+  return ret;
+}
+
+const char *ExtractUptr(const char *str, const char *delims, uptr *result) {
+  char *buff = nullptr;
+  const char *ret = ExtractToken(str, delims, &buff);
+  if (buff) {
+    *result = (uptr)internal_atoll(buff);
+  }
+  InternalFree(buff);
+  return ret;
+}
+
+const char *ExtractSptr(const char *str, const char *delims, sptr *result) {
+  char *buff = nullptr;
+  const char *ret = ExtractToken(str, delims, &buff);
+  if (buff) {
+    *result = (sptr)internal_atoll(buff);
+  }
+  InternalFree(buff);
+  return ret;
+}
+
+const char *ExtractTokenUpToDelimiter(const char *str, const char *delimiter,
+                                      char **result) {
+  const char *found_delimiter = internal_strstr(str, delimiter);
+  uptr prefix_len =
+      found_delimiter ? found_delimiter - str : internal_strlen(str);
+  *result = (char *)InternalAlloc(prefix_len + 1);
+  internal_memcpy(*result, str, prefix_len);
+  (*result)[prefix_len] = '\0';
+  const char *prefix_end = str + prefix_len;
+  if (*prefix_end != '\0') prefix_end += internal_strlen(delimiter);
+  return prefix_end;
+}
+
+SymbolizedStack *Symbolizer::SymbolizePC(uptr addr) {
+  BlockingMutexLock l(&mu_);
+  const char *module_name = nullptr;
+  uptr module_offset;
+  ModuleArch arch;
+  SymbolizedStack *res = SymbolizedStack::New(addr);
+  if (!FindModuleNameAndOffsetForAddress(addr, &module_name, &module_offset,
+                                         &arch))
+    return res;
+  // Always fill data about module name and offset.
+  res->info.FillModuleInfo(module_name, module_offset, arch);
+  for (auto &tool : tools_) {
+    SymbolizerScope sym_scope(this);
+    if (tool.SymbolizePC(addr, res)) {
+      return res;
+    }
+  }
+  return res;
+}
+
+bool Symbolizer::SymbolizeData(uptr addr, DataInfo *info) {
+  BlockingMutexLock l(&mu_);
+  const char *module_name = nullptr;
+  uptr module_offset;
+  ModuleArch arch;
+  if (!FindModuleNameAndOffsetForAddress(addr, &module_name, &module_offset,
+                                         &arch))
+    return false;
+  info->Clear();
+  info->module = internal_strdup(module_name);
+  info->module_offset = module_offset;
+  info->module_arch = arch;
+  for (auto &tool : tools_) {
+    SymbolizerScope sym_scope(this);
+    if (tool.SymbolizeData(addr, info)) {
+      return true;
+    }
+  }
+  return true;
+}
+
+bool Symbolizer::SymbolizeFrame(uptr addr, FrameInfo *info) {
+  BlockingMutexLock l(&mu_);
+  const char *module_name = nullptr;
+  if (!FindModuleNameAndOffsetForAddress(
+          addr, &module_name, &info->module_offset, &info->module_arch))
+    return false;
+  info->module = internal_strdup(module_name);
+  for (auto &tool : tools_) {
+    SymbolizerScope sym_scope(this);
+    if (tool.SymbolizeFrame(addr, info)) {
+      return true;
+    }
+  }
+  return true;
+}
+
+bool Symbolizer::GetModuleNameAndOffsetForPC(uptr pc, const char **module_name,
+                                             uptr *module_address) {
+  BlockingMutexLock l(&mu_);
+  const char *internal_module_name = nullptr;
+  ModuleArch arch;
+  if (!FindModuleNameAndOffsetForAddress(pc, &internal_module_name,
+                                         module_address, &arch))
+    return false;
+
+  if (module_name)
+    *module_name = module_names_.GetOwnedCopy(internal_module_name);
+  return true;
+}
+
+void Symbolizer::Flush() {
+  BlockingMutexLock l(&mu_);
+  for (auto &tool : tools_) {
+    SymbolizerScope sym_scope(this);
+    tool.Flush();
+  }
+}
+
+const char *Symbolizer::Demangle(const char *name) {
+  BlockingMutexLock l(&mu_);
+  for (auto &tool : tools_) {
+    SymbolizerScope sym_scope(this);
+    if (const char *demangled = tool.Demangle(name))
+      return demangled;
+  }
+  return PlatformDemangle(name);
+}
+
+bool Symbolizer::FindModuleNameAndOffsetForAddress(uptr address,
+                                                   const char **module_name,
+                                                   uptr *module_offset,
+                                                   ModuleArch *module_arch) {
+  const LoadedModule *module = FindModuleForAddress(address);
+  if (!module)
+    return false;
+  *module_name = module->full_name();
+  *module_offset = address - module->base_address();
+  *module_arch = module->arch();
+  return true;
+}
+
+void Symbolizer::RefreshModules() {
+  modules_.init();
+  fallback_modules_.fallbackInit();
+  RAW_CHECK(modules_.size() > 0);
+  modules_fresh_ = true;
+}
+
+static const LoadedModule *SearchForModule(const ListOfModules &modules,
+                                           uptr address) {
+  for (uptr i = 0; i < modules.size(); i++) {
+    if (modules[i].containsAddress(address)) {
+      return &modules[i];
+    }
+  }
+  return nullptr;
+}
+
+const LoadedModule *Symbolizer::FindModuleForAddress(uptr address) {
+  bool modules_were_reloaded = false;
+  if (!modules_fresh_) {
+    RefreshModules();
+    modules_were_reloaded = true;
+  }
+  const LoadedModule *module = SearchForModule(modules_, address);
+  if (module) return module;
+
+  // dlopen/dlclose interceptors invalidate the module list, but when
+  // interception is disabled, we need to retry if the lookup fails in
+  // case the module list changed.
+#if !SANITIZER_INTERCEPT_DLOPEN_DLCLOSE
+  if (!modules_were_reloaded) {
+    RefreshModules();
+    module = SearchForModule(modules_, address);
+    if (module) return module;
+  }
+#endif
+
+  if (fallback_modules_.size()) {
+    module = SearchForModule(fallback_modules_, address);
+  }
+  return module;
+}
+
+// For now we assume the following protocol:
+// For each request of the form
+//   <module_name> <module_offset>
+// passed to STDIN, external symbolizer prints to STDOUT response:
+//   <function_name>
+//   <file_name>:<line_number>:<column_number>
+//   <function_name>
+//   <file_name>:<line_number>:<column_number>
+//   ...
+//   <empty line>
+class LLVMSymbolizerProcess : public SymbolizerProcess {
+ public:
+  explicit LLVMSymbolizerProcess(const char *path)
+      : SymbolizerProcess(path, /*use_posix_spawn=*/SANITIZER_MAC) {}
+
+ private:
+  bool ReachedEndOfOutput(const char *buffer, uptr length) const override {
+    // Empty line marks the end of llvm-symbolizer output.
+    return length >= 2 && buffer[length - 1] == '\n' &&
+           buffer[length - 2] == '\n';
+  }
+
+  // When adding a new architecture, don't forget to also update
+  // script/asan_symbolize.py and sanitizer_common.h.
+  void GetArgV(const char *path_to_binary,
+               const char *(&argv)[kArgVMax]) const override {
+#if defined(__x86_64h__)
+    const char* const kSymbolizerArch = "--default-arch=x86_64h";
+#elif defined(__x86_64__)
+    const char* const kSymbolizerArch = "--default-arch=x86_64";
+#elif defined(__i386__)
+    const char* const kSymbolizerArch = "--default-arch=i386";
+#elif defined(__aarch64__)
+    const char* const kSymbolizerArch = "--default-arch=arm64";
+#elif defined(__arm__)
+    const char* const kSymbolizerArch = "--default-arch=arm";
+#elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+    const char* const kSymbolizerArch = "--default-arch=powerpc64";
+#elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+    const char* const kSymbolizerArch = "--default-arch=powerpc64le";
+#elif defined(__s390x__)
+    const char* const kSymbolizerArch = "--default-arch=s390x";
+#elif defined(__s390__)
+    const char* const kSymbolizerArch = "--default-arch=s390";
+#else
+    const char* const kSymbolizerArch = "--default-arch=unknown";
+#endif
+
+    const char *const inline_flag = common_flags()->symbolize_inline_frames
+                                        ? "--inlining=true"
+                                        : "--inlining=false";
+    int i = 0;
+    argv[i++] = path_to_binary;
+    argv[i++] = inline_flag;
+    argv[i++] = kSymbolizerArch;
+    argv[i++] = nullptr;
+  }
+};
+
+LLVMSymbolizer::LLVMSymbolizer(const char *path, LowLevelAllocator *allocator)
+    : symbolizer_process_(new(*allocator) LLVMSymbolizerProcess(path)) {}
+
+// Parse a <file>:<line>[:<column>] buffer. The file path may contain colons on
+// Windows, so extract tokens from the right hand side first. The column info is
+// also optional.
+static const char *ParseFileLineInfo(AddressInfo *info, const char *str) {
+  char *file_line_info = nullptr;
+  str = ExtractToken(str, "\n", &file_line_info);
+  CHECK(file_line_info);
+
+  if (uptr size = internal_strlen(file_line_info)) {
+    char *back = file_line_info + size - 1;
+    for (int i = 0; i < 2; ++i) {
+      while (back > file_line_info && IsDigit(*back)) --back;
+      if (*back != ':' || !IsDigit(back[1])) break;
+      info->column = info->line;
+      info->line = internal_atoll(back + 1);
+      // Truncate the string at the colon to keep only filename.
+      *back = '\0';
+      --back;
+    }
+    ExtractToken(file_line_info, "", &info->file);
+  }
+
+  InternalFree(file_line_info);
+  return str;
+}
+
+// Parses one or more two-line strings in the following format:
+//   <function_name>
+//   <file_name>:<line_number>[:<column_number>]
+// Used by LLVMSymbolizer, Addr2LinePool and InternalSymbolizer, since all of
+// them use the same output format.
+void ParseSymbolizePCOutput(const char *str, SymbolizedStack *res) {
+  bool top_frame = true;
+  SymbolizedStack *last = res;
+  while (true) {
+    char *function_name = nullptr;
+    str = ExtractToken(str, "\n", &function_name);
+    CHECK(function_name);
+    if (function_name[0] == '\0') {
+      // There are no more frames.
+      InternalFree(function_name);
+      break;
+    }
+    SymbolizedStack *cur;
+    if (top_frame) {
+      cur = res;
+      top_frame = false;
+    } else {
+      cur = SymbolizedStack::New(res->info.address);
+      cur->info.FillModuleInfo(res->info.module, res->info.module_offset,
+                               res->info.module_arch);
+      last->next = cur;
+      last = cur;
+    }
+
+    AddressInfo *info = &cur->info;
+    info->function = function_name;
+    str = ParseFileLineInfo(info, str);
+
+    // Functions and filenames can be "??", in which case we write 0
+    // to address info to mark that names are unknown.
+    if (0 == internal_strcmp(info->function, "??")) {
+      InternalFree(info->function);
+      info->function = 0;
+    }
+    if (0 == internal_strcmp(info->file, "??")) {
+      InternalFree(info->file);
+      info->file = 0;
+    }
+  }
+}
+
+// Parses a two-line string in the following format:
+//   <symbol_name>
+//   <start_address> <size>
+// Used by LLVMSymbolizer and InternalSymbolizer.
+void ParseSymbolizeDataOutput(const char *str, DataInfo *info) {
+  str = ExtractToken(str, "\n", &info->name);
+  str = ExtractUptr(str, " ", &info->start);
+  str = ExtractUptr(str, "\n", &info->size);
+}
+
+static void ParseSymbolizeFrameOutput(const char *str,
+                                      InternalMmapVector<LocalInfo> *locals) {
+  if (internal_strncmp(str, "??", 2) == 0)
+    return;
+
+  while (*str) {
+    LocalInfo local;
+    str = ExtractToken(str, "\n", &local.function_name);
+    str = ExtractToken(str, "\n", &local.name);
+
+    AddressInfo addr;
+    str = ParseFileLineInfo(&addr, str);
+    local.decl_file = addr.file;
+    local.decl_line = addr.line;
+
+    local.has_frame_offset = internal_strncmp(str, "??", 2) != 0;
+    str = ExtractSptr(str, " ", &local.frame_offset);
+
+    local.has_size = internal_strncmp(str, "??", 2) != 0;
+    str = ExtractUptr(str, " ", &local.size);
+
+    local.has_tag_offset = internal_strncmp(str, "??", 2) != 0;
+    str = ExtractUptr(str, "\n", &local.tag_offset);
+
+    locals->push_back(local);
+  }
+}
+
+bool LLVMSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
+  AddressInfo *info = &stack->info;
+  const char *buf = FormatAndSendCommand(
+      "CODE", info->module, info->module_offset, info->module_arch);
+  if (!buf)
+    return false;
+  ParseSymbolizePCOutput(buf, stack);
+  return true;
+}
+
+bool LLVMSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
+  const char *buf = FormatAndSendCommand(
+      "DATA", info->module, info->module_offset, info->module_arch);
+  if (!buf)
+    return false;
+  ParseSymbolizeDataOutput(buf, info);
+  info->start += (addr - info->module_offset); // Add the base address.
+  return true;
+}
+
+bool LLVMSymbolizer::SymbolizeFrame(uptr addr, FrameInfo *info) {
+  const char *buf = FormatAndSendCommand(
+      "FRAME", info->module, info->module_offset, info->module_arch);
+  if (!buf)
+    return false;
+  ParseSymbolizeFrameOutput(buf, &info->locals);
+  return true;
+}
+
+const char *LLVMSymbolizer::FormatAndSendCommand(const char *command_prefix,
+                                                 const char *module_name,
+                                                 uptr module_offset,
+                                                 ModuleArch arch) {
+  CHECK(module_name);
+  int size_needed = 0;
+  if (arch == kModuleArchUnknown)
+    size_needed = internal_snprintf(buffer_, kBufferSize, "%s \"%s\" 0x%zx\n",
+                                    command_prefix, module_name, module_offset);
+  else
+    size_needed = internal_snprintf(buffer_, kBufferSize,
+                                    "%s \"%s:%s\" 0x%zx\n", command_prefix,
+                                    module_name, ModuleArchToString(arch),
+                                    module_offset);
+
+  if (size_needed >= static_cast<int>(kBufferSize)) {
+    Report("WARNING: Command buffer too small");
+    return nullptr;
+  }
+
+  return symbolizer_process_->SendCommand(buffer_);
+}
+
+SymbolizerProcess::SymbolizerProcess(const char *path, bool use_posix_spawn)
+    : path_(path),
+      input_fd_(kInvalidFd),
+      output_fd_(kInvalidFd),
+      times_restarted_(0),
+      failed_to_start_(false),
+      reported_invalid_path_(false),
+      use_posix_spawn_(use_posix_spawn) {
+  CHECK(path_);
+  CHECK_NE(path_[0], '\0');
+}
+
+static bool IsSameModule(const char* path) {
+  if (const char* ProcessName = GetProcessName()) {
+    if (const char* SymbolizerName = StripModuleName(path)) {
+      return !internal_strcmp(ProcessName, SymbolizerName);
+    }
+  }
+  return false;
+}
+
+const char *SymbolizerProcess::SendCommand(const char *command) {
+  if (failed_to_start_)
+    return nullptr;
+  if (IsSameModule(path_)) {
+    Report("WARNING: Symbolizer was blocked from starting itself!\n");
+    failed_to_start_ = true;
+    return nullptr;
+  }
+  for (; times_restarted_ < kMaxTimesRestarted; times_restarted_++) {
+    // Start or restart symbolizer if we failed to send command to it.
+    if (const char *res = SendCommandImpl(command))
+      return res;
+    Restart();
+  }
+  if (!failed_to_start_) {
+    Report("WARNING: Failed to use and restart external symbolizer!\n");
+    failed_to_start_ = true;
+  }
+  return nullptr;
+}
+
+const char *SymbolizerProcess::SendCommandImpl(const char *command) {
+  if (input_fd_ == kInvalidFd || output_fd_ == kInvalidFd)
+      return nullptr;
+  if (!WriteToSymbolizer(command, internal_strlen(command)))
+      return nullptr;
+  if (!ReadFromSymbolizer(buffer_, kBufferSize))
+      return nullptr;
+  return buffer_;
+}
+
+bool SymbolizerProcess::Restart() {
+  if (input_fd_ != kInvalidFd)
+    CloseFile(input_fd_);
+  if (output_fd_ != kInvalidFd)
+    CloseFile(output_fd_);
+  return StartSymbolizerSubprocess();
+}
+
+bool SymbolizerProcess::ReadFromSymbolizer(char *buffer, uptr max_length) {
+  if (max_length == 0)
+    return true;
+  uptr read_len = 0;
+  while (true) {
+    uptr just_read = 0;
+    bool success = ReadFromFile(input_fd_, buffer + read_len,
+                                max_length - read_len - 1, &just_read);
+    // We can't read 0 bytes, as we don't expect external symbolizer to close
+    // its stdout.
+    if (!success || just_read == 0) {
+      Report("WARNING: Can't read from symbolizer at fd %d\n", input_fd_);
+      return false;
+    }
+    read_len += just_read;
+    if (ReachedEndOfOutput(buffer, read_len))
+      break;
+    if (read_len + 1 == max_length) {
+      Report("WARNING: Symbolizer buffer too small\n");
+      read_len = 0;
+      break;
+    }
+  }
+  buffer[read_len] = '\0';
+  return true;
+}
+
+bool SymbolizerProcess::WriteToSymbolizer(const char *buffer, uptr length) {
+  if (length == 0)
+    return true;
+  uptr write_len = 0;
+  bool success = WriteToFile(output_fd_, buffer, length, &write_len);
+  if (!success || write_len != length) {
+    Report("WARNING: Can't write to symbolizer at fd %d\n", output_fd_);
+    return false;
+  }
+  return true;
+}
+
+#endif  // !SANITIZER_SYMBOLIZER_MARKUP
+
+}  // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_symbolizer_mac.cpp b/lib/tsan/sanitizer_common/sanitizer_symbolizer_mac.cpp
new file mode 100644
index 0000000000..29cbf62acd
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_symbolizer_mac.cpp
@@ -0,0 +1,249 @@
+//===-- sanitizer_symbolizer_mac.cpp --------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between various sanitizers' runtime libraries.
+//
+// Implementation of Mac-specific "atos" symbolizer.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_MAC
+
+#include "sanitizer_allocator_internal.h"
+#include "sanitizer_mac.h"
+#include "sanitizer_symbolizer_mac.h"
+
+#include <dlfcn.h>
+#include <errno.h>
+#include <mach/mach.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <util.h>
+
+namespace __sanitizer {
+
+bool DlAddrSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
+  Dl_info info;
+  int result = dladdr((const void *)addr, &info);
+  if (!result) return false;
+
+  CHECK(addr >= reinterpret_cast<uptr>(info.dli_saddr));
+  stack->info.function_offset = addr - reinterpret_cast<uptr>(info.dli_saddr);
+  const char *demangled = DemangleSwiftAndCXX(info.dli_sname);
+  if (!demangled) return false;
+  stack->info.function = internal_strdup(demangled);
+  return true;
+}
+
+bool DlAddrSymbolizer::SymbolizeData(uptr addr, DataInfo *datainfo) {
+  Dl_info info;
+  int result = dladdr((const void *)addr, &info);
+  if (!result) return false;
+  const char *demangled = DemangleSwiftAndCXX(info.dli_sname);
+  datainfo->name = internal_strdup(demangled);
+  datainfo->start = (uptr)info.dli_saddr;
+  return true;
+}
+
+#define K_ATOS_ENV_VAR "__check_mach_ports_lookup"
+
+// This cannot live in `AtosSymbolizerProcess` because instances of that object
+// are allocated by the internal allocator which under ASan is poisoned with
+// kAsanInternalHeapMagic.
+static char kAtosMachPortEnvEntry[] = K_ATOS_ENV_VAR "=000000000000000";
+
+class AtosSymbolizerProcess : public SymbolizerProcess {
+ public:
+  explicit AtosSymbolizerProcess(const char *path)
+      : SymbolizerProcess(path, /*use_posix_spawn*/ true) {
+    pid_str_[0] = '\0';
+  }
+
+  void LateInitialize() {
+    if (SANITIZER_IOSSIM) {
+      // `putenv()` may call malloc/realloc so it is only safe to do this
+      // during LateInitialize() or later (i.e. we can't do this in the
+      // constructor).  We also can't do this in `StartSymbolizerSubprocess()`
+      // because in TSan we switch allocators when we're symbolizing.
+      // We use `putenv()` rather than `setenv()` so that we can later directly
+      // write into the storage without LibC getting involved to change what the
+      // variable is set to
+      int result = putenv(kAtosMachPortEnvEntry);
+      CHECK_EQ(result, 0);
+    }
+  }
+
+ private:
+  bool StartSymbolizerSubprocess() override {
+    // Configure sandbox before starting atos process.
+
+    // Put the string command line argument in the object so that it outlives
+    // the call to GetArgV.
+    internal_snprintf(pid_str_, sizeof(pid_str_), "%d", internal_getpid());
+
+    if (SANITIZER_IOSSIM) {
+      // `atos` in the simulator is restricted in its ability to retrieve the
+      // task port for the target process (us) so we need to do extra work
+      // to pass our task port to it.
+      mach_port_t ports[]{mach_task_self()};
+      kern_return_t ret =
+          mach_ports_register(mach_task_self(), ports, /*count=*/1);
+      CHECK_EQ(ret, KERN_SUCCESS);
+
+      // Set environment variable that signals to `atos` that it should look
+      // for our task port. We can't call `setenv()` here because it might call
+      // malloc/realloc. To avoid that we instead update the
+      // `mach_port_env_var_entry_` variable with our current PID.
+      uptr count = internal_snprintf(kAtosMachPortEnvEntry,
+                                     sizeof(kAtosMachPortEnvEntry),
+                                     K_ATOS_ENV_VAR "=%s", pid_str_);
+      CHECK_GE(count, sizeof(K_ATOS_ENV_VAR) + internal_strlen(pid_str_));
+      // Document our assumption but without calling `getenv()` in normal
+      // builds.
+      DCHECK(getenv(K_ATOS_ENV_VAR));
+      DCHECK_EQ(internal_strcmp(getenv(K_ATOS_ENV_VAR), pid_str_), 0);
+    }
+
+    return SymbolizerProcess::StartSymbolizerSubprocess();
+  }
+
+  bool ReachedEndOfOutput(const char *buffer, uptr length) const override {
+    return (length >= 1 && buffer[length - 1] == '\n');
+  }
+
+  void GetArgV(const char *path_to_binary,
+               const char *(&argv)[kArgVMax]) const override {
+    int i = 0;
+    argv[i++] = path_to_binary;
+    argv[i++] = "-p";
+    argv[i++] = &pid_str_[0];
+    if (GetMacosAlignedVersion() == MacosVersion(10, 9)) {
+      // On Mavericks atos prints a deprecation warning which we suppress by
+      // passing -d. The warning isn't present on other OSX versions, even the
+      // newer ones.
+      argv[i++] = "-d";
+    }
+    argv[i++] = nullptr;
+  }
+
+  char pid_str_[16];
+  // Space for `\0` in `K_ATOS_ENV_VAR` is reused for `=`.
+  static_assert(sizeof(kAtosMachPortEnvEntry) ==
+                    (sizeof(K_ATOS_ENV_VAR) + sizeof(pid_str_)),
+                "sizes should match");
+};
+
+#undef K_ATOS_ENV_VAR
+
+static bool ParseCommandOutput(const char *str, uptr addr, char **out_name,
+                               char **out_module, char **out_file, uptr *line,
+                               uptr *start_address) {
+  // Trim ending newlines.
+  char *trim;
+  ExtractTokenUpToDelimiter(str, "\n", &trim);
+
+  // The line from `atos` is in one of these formats:
+  //   myfunction (in library.dylib) (sourcefile.c:17)
+  //   myfunction (in library.dylib) + 0x1fe
+  //   myfunction (in library.dylib) + 15
+  //   0xdeadbeef (in library.dylib) + 0x1fe
+  //   0xdeadbeef (in library.dylib) + 15
+  //   0xdeadbeef (in library.dylib)
+  //   0xdeadbeef
+
+  const char *rest = trim;
+  char *symbol_name;
+  rest = ExtractTokenUpToDelimiter(rest, " (in ", &symbol_name);
+  if (rest[0] == '\0') {
+    InternalFree(symbol_name);
+    InternalFree(trim);
+    return false;
+  }
+
+  if (internal_strncmp(symbol_name, "0x", 2) != 0)
+    *out_name = symbol_name;
+  else
+    InternalFree(symbol_name);
+  rest = ExtractTokenUpToDelimiter(rest, ") ", out_module);
+
+  if (rest[0] == '(') {
+    if (out_file) {
+      rest++;
+      rest = ExtractTokenUpToDelimiter(rest, ":", out_file);
+      char *extracted_line_number;
+      rest = ExtractTokenUpToDelimiter(rest, ")", &extracted_line_number);
+      if (line) *line = (uptr)internal_atoll(extracted_line_number);
+      InternalFree(extracted_line_number);
+    }
+  } else if (rest[0] == '+') {
+    rest += 2;
+    uptr offset = internal_atoll(rest);
+    if (start_address) *start_address = addr - offset;
+  }
+
+  InternalFree(trim);
+  return true;
+}
+
+AtosSymbolizer::AtosSymbolizer(const char *path, LowLevelAllocator *allocator)
+    : process_(new (*allocator) AtosSymbolizerProcess(path)) {}
+
+bool AtosSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
+  if (!process_) return false;
+  if (addr == 0) return false;
+  char command[32];
+  internal_snprintf(command, sizeof(command), "0x%zx\n", addr);
+  const char *buf = process_->SendCommand(command);
+  if (!buf) return false;
+  uptr line;
+  uptr start_address = AddressInfo::kUnknown;
+  if (!ParseCommandOutput(buf, addr, &stack->info.function, &stack->info.module,
+                          &stack->info.file, &line, &start_address)) {
+    process_ = nullptr;
+    return false;
+  }
+  stack->info.line = (int)line;
+
+  if (start_address == AddressInfo::kUnknown) {
+    // Fallback to dladdr() to get function start address if atos doesn't report
+    // it.
+    Dl_info info;
+    int result = dladdr((const void *)addr, &info);
+    if (result)
+      start_address = reinterpret_cast<uptr>(info.dli_saddr);
+  }
+
+  // Only assig to `function_offset` if we were able to get the function's
+  // start address.
+  if (start_address != AddressInfo::kUnknown) {
+    CHECK(addr >= start_address);
+    stack->info.function_offset = addr - start_address;
+  }
+  return true;
+}
+
+bool AtosSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
+  if (!process_) return false;
+  char command[32];
+  internal_snprintf(command, sizeof(command), "0x%zx\n", addr);
+  const char *buf = process_->SendCommand(command);
+  if (!buf) return false;
+  if (!ParseCommandOutput(buf, addr, &info->name, &info->module, nullptr,
+                          nullptr, &info->start)) {
+    process_ = nullptr;
+    return false;
+  }
+  return true;
+}
+
+void AtosSymbolizer::LateInitialize() { process_->LateInitialize(); }
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_MAC
diff --git a/lib/tsan/sanitizer_common/sanitizer_symbolizer_markup.cpp b/lib/tsan/sanitizer_common/sanitizer_symbolizer_markup.cpp
new file mode 100644
index 0000000000..2963af9536
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_symbolizer_markup.cpp
@@ -0,0 +1,146 @@
+//===-- sanitizer_symbolizer_markup.cpp -----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between various sanitizers' runtime libraries.
+//
+// Implementation of offline markup symbolizer.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_SYMBOLIZER_MARKUP
+
+#if SANITIZER_FUCHSIA
+#include "sanitizer_symbolizer_fuchsia.h"
+#elif SANITIZER_RTEMS
+#include "sanitizer_symbolizer_rtems.h"
+#endif
+#include "sanitizer_stacktrace.h"
+#include "sanitizer_symbolizer.h"
+
+#include <limits.h>
+#include <unwind.h>
+
+namespace __sanitizer {
+
+// This generic support for offline symbolizing is based on the
+// Fuchsia port.  We don't do any actual symbolization per se.
+// Instead, we emit text containing raw addresses and raw linkage
+// symbol names, embedded in Fuchsia's symbolization markup format.
+// Fuchsia's logging infrastructure emits enough information about
+// process memory layout that a post-processing filter can do the
+// symbolization and pretty-print the markup.  See the spec at:
+// https://fuchsia.googlesource.com/zircon/+/master/docs/symbolizer_markup.md
+
+// This is used by UBSan for type names, and by ASan for global variable names.
+// It's expected to return a static buffer that will be reused on each call.
+const char *Symbolizer::Demangle(const char *name) {
+  static char buffer[kFormatDemangleMax];
+  internal_snprintf(buffer, sizeof(buffer), kFormatDemangle, name);
+  return buffer;
+}
+
+// This is used mostly for suppression matching.  Making it work
+// would enable "interceptor_via_lib" suppressions.  It's also used
+// once in UBSan to say "in module ..." in a message that also
+// includes an address in the module, so post-processing can already
+// pretty-print that so as to indicate the module.
+bool Symbolizer::GetModuleNameAndOffsetForPC(uptr pc, const char **module_name,
+                                             uptr *module_address) {
+  return false;
+}
+
+// This is used in some places for suppression checking, which we
+// don't really support for Fuchsia.  It's also used in UBSan to
+// identify a PC location to a function name, so we always fill in
+// the function member with a string containing markup around the PC
+// value.
+// TODO(mcgrathr): Under SANITIZER_GO, it's currently used by TSan
+// to render stack frames, but that should be changed to use
+// RenderStackFrame.
+SymbolizedStack *Symbolizer::SymbolizePC(uptr addr) {
+  SymbolizedStack *s = SymbolizedStack::New(addr);
+  char buffer[kFormatFunctionMax];
+  internal_snprintf(buffer, sizeof(buffer), kFormatFunction, addr);
+  s->info.function = internal_strdup(buffer);
+  return s;
+}
+
+// Always claim we succeeded, so that RenderDataInfo will be called.
+bool Symbolizer::SymbolizeData(uptr addr, DataInfo *info) {
+  info->Clear();
+  info->start = addr;
+  return true;
+}
+
+// We ignore the format argument to __sanitizer_symbolize_global.
+void RenderData(InternalScopedString *buffer, const char *format,
+                const DataInfo *DI, const char *strip_path_prefix) {
+  buffer->append(kFormatData, DI->start);
+}
+
+// We don't support the stack_trace_format flag at all.
+void RenderFrame(InternalScopedString *buffer, const char *format, int frame_no,
+                 const AddressInfo &info, bool vs_style,
+                 const char *strip_path_prefix, const char *strip_func_prefix) {
+  buffer->append(kFormatFrame, frame_no, info.address);
+}
+
+Symbolizer *Symbolizer::PlatformInit() {
+  return new (symbolizer_allocator_) Symbolizer({});
+}
+
+void Symbolizer::LateInitialize() {
+  Symbolizer::GetOrInit()->LateInitializeTools();
+}
+
+void StartReportDeadlySignal() {}
+void ReportDeadlySignal(const SignalContext &sig, u32 tid,
+                        UnwindSignalStackCallbackType unwind,
+                        const void *unwind_context) {}
+
+#if SANITIZER_CAN_SLOW_UNWIND
+struct UnwindTraceArg {
+  BufferedStackTrace *stack;
+  u32 max_depth;
+};
+
+_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
+  UnwindTraceArg *arg = static_cast<UnwindTraceArg *>(param);
+  CHECK_LT(arg->stack->size, arg->max_depth);
+  uptr pc = _Unwind_GetIP(ctx);
+  if (pc < PAGE_SIZE) return _URC_NORMAL_STOP;
+  arg->stack->trace_buffer[arg->stack->size++] = pc;
+  return (arg->stack->size == arg->max_depth ? _URC_NORMAL_STOP
+                                             : _URC_NO_REASON);
+}
+
+void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
+  CHECK_GE(max_depth, 2);
+  size = 0;
+  UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
+  _Unwind_Backtrace(Unwind_Trace, &arg);
+  CHECK_GT(size, 0);
+  // We need to pop a few frames so that pc is on top.
+  uptr to_pop = LocatePcInTrace(pc);
+  // trace_buffer[0] belongs to the current function so we always pop it,
+  // unless there is only 1 frame in the stack trace (1 frame is always better
+  // than 0!).
+  PopStackFrames(Min(to_pop, static_cast<uptr>(1)));
+  trace_buffer[0] = pc;
+}
+
+void BufferedStackTrace::UnwindSlow(uptr pc, void *context, u32 max_depth) {
+  CHECK(context);
+  CHECK_GE(max_depth, 2);
+  UNREACHABLE("signal context doesn't exist");
+}
+#endif  // SANITIZER_CAN_SLOW_UNWIND
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_SYMBOLIZER_MARKUP
diff --git a/lib/tsan/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
new file mode 100644
index 0000000000..3c379a8480
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
@@ -0,0 +1,492 @@
+//===-- sanitizer_symbolizer_posix_libcdep.cpp ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+// POSIX-specific implementation of symbolizer parts.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_POSIX
+#include "sanitizer_allocator_internal.h"
+#include "sanitizer_common.h"
+#include "sanitizer_file.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_internal_defs.h"
+#include "sanitizer_linux.h"
+#include "sanitizer_placement_new.h"
+#include "sanitizer_posix.h"
+#include "sanitizer_procmaps.h"
+#include "sanitizer_symbolizer_internal.h"
+#include "sanitizer_symbolizer_libbacktrace.h"
+#include "sanitizer_symbolizer_mac.h"
+
+#include <dlfcn.h>   // for dlsym()
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+// C++ demangling function, as required by Itanium C++ ABI. This is weak,
+// because we do not require a C++ ABI library to be linked to a program
+// using sanitizers; if it's not present, we'll just use the mangled name.
+namespace __cxxabiv1 {
+  extern "C" SANITIZER_WEAK_ATTRIBUTE
+  char *__cxa_demangle(const char *mangled, char *buffer,
+                                  size_t *length, int *status);
+}
+
+namespace __sanitizer {
+
+// Attempts to demangle the name via __cxa_demangle from __cxxabiv1.
+const char *DemangleCXXABI(const char *name) {
+  // FIXME: __cxa_demangle aggressively insists on allocating memory.
+  // There's not much we can do about that, short of providing our
+  // own demangler (libc++abi's implementation could be adapted so that
+  // it does not allocate). For now, we just call it anyway, and we leak
+  // the returned value.
+  if (&__cxxabiv1::__cxa_demangle)
+    if (const char *demangled_name =
+          __cxxabiv1::__cxa_demangle(name, 0, 0, 0))
+      return demangled_name;
+
+  return name;
+}
+
+// As of now, there are no headers for the Swift runtime. Once they are
+// present, we will weakly link since we do not require Swift runtime to be
+// linked.
+typedef char *(*swift_demangle_ft)(const char *mangledName,
+                                   size_t mangledNameLength, char *outputBuffer,
+                                   size_t *outputBufferSize, uint32_t flags);
+static swift_demangle_ft swift_demangle_f;
+
+// This must not happen lazily at symbolication time, because dlsym uses
+// malloc and thread-local storage, which is not a good thing to do during
+// symbolication.
+static void InitializeSwiftDemangler() {
+  swift_demangle_f = (swift_demangle_ft)dlsym(RTLD_DEFAULT, "swift_demangle");
+  (void)dlerror(); // Cleanup error message in case of failure
+}
+
+// Attempts to demangle a Swift name. The demangler will return nullptr if a
+// non-Swift name is passed in.
+const char *DemangleSwift(const char *name) {
+  if (swift_demangle_f)
+    return swift_demangle_f(name, internal_strlen(name), 0, 0, 0);
+
+  return nullptr;
+}
+
+const char *DemangleSwiftAndCXX(const char *name) {
+  if (!name) return nullptr;
+  if (const char *swift_demangled_name = DemangleSwift(name))
+    return swift_demangled_name;
+  return DemangleCXXABI(name);
+}
+
+static bool CreateTwoHighNumberedPipes(int *infd_, int *outfd_) {
+  int *infd = NULL;
+  int *outfd = NULL;
+  // The client program may close its stdin and/or stdout and/or stderr
+  // thus allowing socketpair to reuse file descriptors 0, 1 or 2.
+  // In this case the communication between the forked processes may be
+  // broken if either the parent or the child tries to close or duplicate
+  // these descriptors. The loop below produces two pairs of file
+  // descriptors, each greater than 2 (stderr).
+  int sock_pair[5][2];
+  for (int i = 0; i < 5; i++) {
+    if (pipe(sock_pair[i]) == -1) {
+      for (int j = 0; j < i; j++) {
+        internal_close(sock_pair[j][0]);
+        internal_close(sock_pair[j][1]);
+      }
+      return false;
+    } else if (sock_pair[i][0] > 2 && sock_pair[i][1] > 2) {
+      if (infd == NULL) {
+        infd = sock_pair[i];
+      } else {
+        outfd = sock_pair[i];
+        for (int j = 0; j < i; j++) {
+          if (sock_pair[j] == infd) continue;
+          internal_close(sock_pair[j][0]);
+          internal_close(sock_pair[j][1]);
+        }
+        break;
+      }
+    }
+  }
+  CHECK(infd);
+  CHECK(outfd);
+  infd_[0] = infd[0];
+  infd_[1] = infd[1];
+  outfd_[0] = outfd[0];
+  outfd_[1] = outfd[1];
+  return true;
+}
+
+bool SymbolizerProcess::StartSymbolizerSubprocess() {
+  if (!FileExists(path_)) {
+    if (!reported_invalid_path_) {
+      Report("WARNING: invalid path to external symbolizer!\n");
+      reported_invalid_path_ = true;
+    }
+    return false;
+  }
+
+  const char *argv[kArgVMax];
+  GetArgV(path_, argv);
+  pid_t pid;
+
+  // Report how symbolizer is being launched for debugging purposes.
+  if (Verbosity() >= 3) {
+    // Only use `Report` for first line so subsequent prints don't get prefixed
+    // with current PID.
+    Report("Launching Symbolizer process: ");
+    for (unsigned index = 0; index < kArgVMax && argv[index]; ++index)
+      Printf("%s ", argv[index]);
+    Printf("\n");
+  }
+
+  if (use_posix_spawn_) {
+#if SANITIZER_MAC
+    fd_t fd = internal_spawn(argv, const_cast<const char **>(GetEnvP()), &pid);
+    if (fd == kInvalidFd) {
+      Report("WARNING: failed to spawn external symbolizer (errno: %d)\n",
+             errno);
+      return false;
+    }
+
+    input_fd_ = fd;
+    output_fd_ = fd;
+#else  // SANITIZER_MAC
+    UNIMPLEMENTED();
+#endif  // SANITIZER_MAC
+  } else {
+    fd_t infd[2] = {}, outfd[2] = {};
+    if (!CreateTwoHighNumberedPipes(infd, outfd)) {
+      Report("WARNING: Can't create a socket pair to start "
+             "external symbolizer (errno: %d)\n", errno);
+      return false;
+    }
+
+    pid = StartSubprocess(path_, argv, GetEnvP(), /* stdin */ outfd[0],
+                          /* stdout */ infd[1]);
+    if (pid < 0) {
+      internal_close(infd[0]);
+      internal_close(outfd[1]);
+      return false;
+    }
+
+    input_fd_ = infd[0];
+    output_fd_ = outfd[1];
+  }
+
+  CHECK_GT(pid, 0);
+
+  // Check that symbolizer subprocess started successfully.
+  SleepForMillis(kSymbolizerStartupTimeMillis);
+  if (!IsProcessRunning(pid)) {
+    // Either waitpid failed, or child has already exited.
+    Report("WARNING: external symbolizer didn't start up correctly!\n");
+    return false;
+  }
+
+  return true;
+}
+
+class Addr2LineProcess : public SymbolizerProcess {
+ public:
+  Addr2LineProcess(const char *path, const char *module_name)
+      : SymbolizerProcess(path), module_name_(internal_strdup(module_name)) {}
+
+  const char *module_name() const { return module_name_; }
+
+ private:
+  void GetArgV(const char *path_to_binary,
+               const char *(&argv)[kArgVMax]) const override {
+    int i = 0;
+    argv[i++] = path_to_binary;
+    argv[i++] = "-iCfe";
+    argv[i++] = module_name_;
+    argv[i++] = nullptr;
+  }
+
+  bool ReachedEndOfOutput(const char *buffer, uptr length) const override;
+
+  bool ReadFromSymbolizer(char *buffer, uptr max_length) override {
+    if (!SymbolizerProcess::ReadFromSymbolizer(buffer, max_length))
+      return false;
+    // The returned buffer is empty when output is valid, but exceeds
+    // max_length.
+    if (*buffer == '\0')
+      return true;
+    // We should cut out output_terminator_ at the end of given buffer,
+    // appended by addr2line to mark the end of its meaningful output.
+    // We cannot scan buffer from it's beginning, because it is legal for it
+    // to start with output_terminator_ in case given offset is invalid. So,
+    // scanning from second character.
+    char *garbage = internal_strstr(buffer + 1, output_terminator_);
+    // This should never be NULL since buffer must end up with
+    // output_terminator_.
+    CHECK(garbage);
+    // Trim the buffer.
+    garbage[0] = '\0';
+    return true;
+  }
+
+  const char *module_name_;  // Owned, leaked.
+  static const char output_terminator_[];
+};
+
+const char Addr2LineProcess::output_terminator_[] = "??\n??:0\n";
+
+bool Addr2LineProcess::ReachedEndOfOutput(const char *buffer,
+                                          uptr length) const {
+  const size_t kTerminatorLen = sizeof(output_terminator_) - 1;
+  // Skip, if we read just kTerminatorLen bytes, because Addr2Line output
+  // should consist at least of two pairs of lines:
+  // 1. First one, corresponding to given offset to be symbolized
+  // (may be equal to output_terminator_, if offset is not valid).
+  // 2. Second one for output_terminator_, itself to mark the end of output.
+  if (length <= kTerminatorLen) return false;
+  // Addr2Line output should end up with output_terminator_.
+  return !internal_memcmp(buffer + length - kTerminatorLen,
+                          output_terminator_, kTerminatorLen);
+}
+
+class Addr2LinePool : public SymbolizerTool {
+ public:
+  explicit Addr2LinePool(const char *addr2line_path,
+                         LowLevelAllocator *allocator)
+      : addr2line_path_(addr2line_path), allocator_(allocator) {
+    addr2line_pool_.reserve(16);
+  }
+
+  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override {
+    if (const char *buf =
+            SendCommand(stack->info.module, stack->info.module_offset)) {
+      ParseSymbolizePCOutput(buf, stack);
+      return true;
+    }
+    return false;
+  }
+
+  bool SymbolizeData(uptr addr, DataInfo *info) override {
+    return false;
+  }
+
+ private:
+  const char *SendCommand(const char *module_name, uptr module_offset) {
+    Addr2LineProcess *addr2line = 0;
+    for (uptr i = 0; i < addr2line_pool_.size(); ++i) {
+      if (0 ==
+          internal_strcmp(module_name, addr2line_pool_[i]->module_name())) {
+        addr2line = addr2line_pool_[i];
+        break;
+      }
+    }
+    if (!addr2line) {
+      addr2line =
+          new(*allocator_) Addr2LineProcess(addr2line_path_, module_name);
+      addr2line_pool_.push_back(addr2line);
+    }
+    CHECK_EQ(0, internal_strcmp(module_name, addr2line->module_name()));
+    char buffer[kBufferSize];
+    internal_snprintf(buffer, kBufferSize, "0x%zx\n0x%zx\n",
+                      module_offset, dummy_address_);
+    return addr2line->SendCommand(buffer);
+  }
+
+  static const uptr kBufferSize = 64;
+  const char *addr2line_path_;
+  LowLevelAllocator *allocator_;
+  InternalMmapVector<Addr2LineProcess*> addr2line_pool_;
+  static const uptr dummy_address_ =
+      FIRST_32_SECOND_64(UINT32_MAX, UINT64_MAX);
+};
+
+#if SANITIZER_SUPPORTS_WEAK_HOOKS
+extern "C" {
+SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE bool
+__sanitizer_symbolize_code(const char *ModuleName, u64 ModuleOffset,
+                           char *Buffer, int MaxLength,
+                           bool SymbolizeInlineFrames);
+SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
+bool __sanitizer_symbolize_data(const char *ModuleName, u64 ModuleOffset,
+                                char *Buffer, int MaxLength);
+SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
+void __sanitizer_symbolize_flush();
+SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
+int __sanitizer_symbolize_demangle(const char *Name, char *Buffer,
+                                   int MaxLength);
+}  // extern "C"
+
+class InternalSymbolizer : public SymbolizerTool {
+ public:
+  static InternalSymbolizer *get(LowLevelAllocator *alloc) {
+    if (__sanitizer_symbolize_code != 0 &&
+        __sanitizer_symbolize_data != 0) {
+      return new(*alloc) InternalSymbolizer();
+    }
+    return 0;
+  }
+
+  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override {
+    bool result = __sanitizer_symbolize_code(
+        stack->info.module, stack->info.module_offset, buffer_, kBufferSize,
+        common_flags()->symbolize_inline_frames);
+    if (result) ParseSymbolizePCOutput(buffer_, stack);
+    return result;
+  }
+
+  bool SymbolizeData(uptr addr, DataInfo *info) override {
+    bool result = __sanitizer_symbolize_data(info->module, info->module_offset,
+                                             buffer_, kBufferSize);
+    if (result) {
+      ParseSymbolizeDataOutput(buffer_, info);
+      info->start += (addr - info->module_offset);  // Add the base address.
+    }
+    return result;
+  }
+
+  void Flush() override {
+    if (__sanitizer_symbolize_flush)
+      __sanitizer_symbolize_flush();
+  }
+
+  const char *Demangle(const char *name) override {
+    if (__sanitizer_symbolize_demangle) {
+      for (uptr res_length = 1024;
+           res_length <= InternalSizeClassMap::kMaxSize;) {
+        char *res_buff = static_cast<char*>(InternalAlloc(res_length));
+        uptr req_length =
+            __sanitizer_symbolize_demangle(name, res_buff, res_length);
+        if (req_length > res_length) {
+          res_length = req_length + 1;
+          InternalFree(res_buff);
+          continue;
+        }
+        return res_buff;
+      }
+    }
+    return name;
+  }
+
+ private:
+  InternalSymbolizer() { }
+
+  static const int kBufferSize = 16 * 1024;
+  char buffer_[kBufferSize];
+};
+#else  // SANITIZER_SUPPORTS_WEAK_HOOKS
+
+class InternalSymbolizer : public SymbolizerTool {
+ public:
+  static InternalSymbolizer *get(LowLevelAllocator *alloc) { return 0; }
+};
+
+#endif  // SANITIZER_SUPPORTS_WEAK_HOOKS
+
+const char *Symbolizer::PlatformDemangle(const char *name) {
+  return DemangleSwiftAndCXX(name);
+}
+
+static SymbolizerTool *ChooseExternalSymbolizer(LowLevelAllocator *allocator) {
+  const char *path = common_flags()->external_symbolizer_path;
+  const char *binary_name = path ? StripModuleName(path) : "";
+  if (path && path[0] == '\0') {
+    VReport(2, "External symbolizer is explicitly disabled.\n");
+    return nullptr;
+  } else if (!internal_strcmp(binary_name, "llvm-symbolizer")) {
+    VReport(2, "Using llvm-symbolizer at user-specified path: %s\n", path);
+    return new(*allocator) LLVMSymbolizer(path, allocator);
+  } else if (!internal_strcmp(binary_name, "atos")) {
+#if SANITIZER_MAC
+    VReport(2, "Using atos at user-specified path: %s\n", path);
+    return new(*allocator) AtosSymbolizer(path, allocator);
+#else  // SANITIZER_MAC
+    Report("ERROR: Using `atos` is only supported on Darwin.\n");
+    Die();
+#endif  // SANITIZER_MAC
+  } else if (!internal_strcmp(binary_name, "addr2line")) {
+    VReport(2, "Using addr2line at user-specified path: %s\n", path);
+    return new(*allocator) Addr2LinePool(path, allocator);
+  } else if (path) {
+    Report("ERROR: External symbolizer path is set to '%s' which isn't "
+           "a known symbolizer. Please set the path to the llvm-symbolizer "
+           "binary or other known tool.\n", path);
+    Die();
+  }
+
+  // Otherwise symbolizer program is unknown, let's search $PATH
+  CHECK(path == nullptr);
+#if SANITIZER_MAC
+  if (const char *found_path = FindPathToBinary("atos")) {
+    VReport(2, "Using atos found at: %s\n", found_path);
+    return new(*allocator) AtosSymbolizer(found_path, allocator);
+  }
+#endif  // SANITIZER_MAC
+  if (const char *found_path = FindPathToBinary("llvm-symbolizer")) {
+    VReport(2, "Using llvm-symbolizer found at: %s\n", found_path);
+    return new(*allocator) LLVMSymbolizer(found_path, allocator);
+  }
+  if (common_flags()->allow_addr2line) {
+    if (const char *found_path = FindPathToBinary("addr2line")) {
+      VReport(2, "Using addr2line found at: %s\n", found_path);
+      return new(*allocator) Addr2LinePool(found_path, allocator);
+    }
+  }
+  return nullptr;
+}
+
+static void ChooseSymbolizerTools(IntrusiveList<SymbolizerTool> *list,
+                                  LowLevelAllocator *allocator) {
+  if (!common_flags()->symbolize) {
+    VReport(2, "Symbolizer is disabled.\n");
+    return;
+  }
+  if (IsAllocatorOutOfMemory()) {
+    VReport(2, "Cannot use internal symbolizer: out of memory\n");
+  } else if (SymbolizerTool *tool = InternalSymbolizer::get(allocator)) {
+    VReport(2, "Using internal symbolizer.\n");
+    list->push_back(tool);
+    return;
+  }
+  if (SymbolizerTool *tool = LibbacktraceSymbolizer::get(allocator)) {
+    VReport(2, "Using libbacktrace symbolizer.\n");
+    list->push_back(tool);
+    return;
+  }
+
+  if (SymbolizerTool *tool = ChooseExternalSymbolizer(allocator)) {
+    list->push_back(tool);
+  }
+
+#if SANITIZER_MAC
+  VReport(2, "Using dladdr symbolizer.\n");
+  list->push_back(new(*allocator) DlAddrSymbolizer());
+#endif  // SANITIZER_MAC
+}
+
+Symbolizer *Symbolizer::PlatformInit() {
+  IntrusiveList<SymbolizerTool> list;
+  list.clear();
+  ChooseSymbolizerTools(&list, &symbolizer_allocator_);
+  return new(symbolizer_allocator_) Symbolizer(list);
+}
+
+void Symbolizer::LateInitialize() {
+  Symbolizer::GetOrInit()->LateInitializeTools();
+  InitializeSwiftDemangler();
+}
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_POSIX
diff --git a/lib/tsan/sanitizer_common/sanitizer_symbolizer_report.cpp b/lib/tsan/sanitizer_common/sanitizer_symbolizer_report.cpp
new file mode 100644
index 0000000000..c26724ceb7
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_symbolizer_report.cpp
@@ -0,0 +1,293 @@
+//===-- sanitizer_symbolizer_report.cpp -----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// This file is shared between AddressSanitizer and other sanitizer run-time
+/// libraries and implements symbolized reports related functions.
+///
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common.h"
+#include "sanitizer_file.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_procmaps.h"
+#include "sanitizer_report_decorator.h"
+#include "sanitizer_stacktrace.h"
+#include "sanitizer_stacktrace_printer.h"
+#include "sanitizer_symbolizer.h"
+
+#if SANITIZER_POSIX
+# include "sanitizer_posix.h"
+# include <sys/mman.h>
+#endif
+
+namespace __sanitizer {
+
+#if !SANITIZER_GO
+void ReportErrorSummary(const char *error_type, const AddressInfo &info,
+                        const char *alt_tool_name) {
+  if (!common_flags()->print_summary) return;
+  InternalScopedString buff(kMaxSummaryLength);
+  buff.append("%s ", error_type);
+  RenderFrame(&buff, "%L %F", 0, info, common_flags()->symbolize_vs_style,
+              common_flags()->strip_path_prefix);
+  ReportErrorSummary(buff.data(), alt_tool_name);
+}
+#endif
+
+#if !SANITIZER_FUCHSIA
+
+bool ReportFile::SupportsColors() {
+  SpinMutexLock l(mu);
+  ReopenIfNecessary();
+  return SupportsColoredOutput(fd);
+}
+
+static INLINE bool ReportSupportsColors() {
+  return report_file.SupportsColors();
+}
+
+#else  // SANITIZER_FUCHSIA
+
+// Fuchsia's logs always go through post-processing that handles colorization.
+static INLINE bool ReportSupportsColors() { return true; }
+
+#endif  // !SANITIZER_FUCHSIA
+
+bool ColorizeReports() {
+  // FIXME: Add proper Windows support to AnsiColorDecorator and re-enable color
+  // printing on Windows.
+  if (SANITIZER_WINDOWS)
+    return false;
+
+  const char *flag = common_flags()->color;
+  return internal_strcmp(flag, "always") == 0 ||
+         (internal_strcmp(flag, "auto") == 0 && ReportSupportsColors());
+}
+
+void ReportErrorSummary(const char *error_type, const StackTrace *stack,
+                        const char *alt_tool_name) {
+#if !SANITIZER_GO
+  if (!common_flags()->print_summary)
+    return;
+  if (stack->size == 0) {
+    ReportErrorSummary(error_type);
+    return;
+  }
+  // Currently, we include the first stack frame into the report summary.
+  // Maybe sometimes we need to choose another frame (e.g. skip memcpy/etc).
+  uptr pc = StackTrace::GetPreviousInstructionPc(stack->trace[0]);
+  SymbolizedStack *frame = Symbolizer::GetOrInit()->SymbolizePC(pc);
+  ReportErrorSummary(error_type, frame->info, alt_tool_name);
+  frame->ClearAll();
+#endif
+}
+
+void ReportMmapWriteExec(int prot) {
+#if SANITIZER_POSIX && (!SANITIZER_GO && !SANITIZER_ANDROID)
+  if ((prot & (PROT_WRITE | PROT_EXEC)) != (PROT_WRITE | PROT_EXEC))
+    return;
+
+  ScopedErrorReportLock l;
+  SanitizerCommonDecorator d;
+
+  InternalMmapVector<BufferedStackTrace> stack_buffer(1);
+  BufferedStackTrace *stack = stack_buffer.data();
+  stack->Reset();
+  uptr top = 0;
+  uptr bottom = 0;
+  GET_CALLER_PC_BP_SP;
+  (void)sp;
+  bool fast = common_flags()->fast_unwind_on_fatal;
+  if (StackTrace::WillUseFastUnwind(fast)) {
+    GetThreadStackTopAndBottom(false, &top, &bottom);
+    stack->Unwind(kStackTraceMax, pc, bp, nullptr, top, bottom, true);
+  } else {
+    stack->Unwind(kStackTraceMax, pc, 0, nullptr, 0, 0, false);
+  }
+
+  Printf("%s", d.Warning());
+  Report("WARNING: %s: writable-executable page usage\n", SanitizerToolName);
+  Printf("%s", d.Default());
+
+  stack->Print();
+  ReportErrorSummary("w-and-x-usage", stack);
+#endif
+}
+
+#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_GO
+void StartReportDeadlySignal() {
+  // Write the first message using fd=2, just in case.
+  // It may actually fail to write in case stderr is closed.
+  CatastrophicErrorWrite(SanitizerToolName, internal_strlen(SanitizerToolName));
+  static const char kDeadlySignal[] = ":DEADLYSIGNAL\n";
+  CatastrophicErrorWrite(kDeadlySignal, sizeof(kDeadlySignal) - 1);
+}
+
+static void MaybeReportNonExecRegion(uptr pc) {
+#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD
+  MemoryMappingLayout proc_maps(/*cache_enabled*/ true);
+  MemoryMappedSegment segment;
+  while (proc_maps.Next(&segment)) {
+    if (pc >= segment.start && pc < segment.end && !segment.IsExecutable())
+      Report("Hint: PC is at a non-executable region. Maybe a wild jump?\n");
+  }
+#endif
+}
+
+static void PrintMemoryByte(InternalScopedString *str, const char *before,
+                            u8 byte) {
+  SanitizerCommonDecorator d;
+  str->append("%s%s%x%x%s ", before, d.MemoryByte(), byte >> 4, byte & 15,
+              d.Default());
+}
+
+static void MaybeDumpInstructionBytes(uptr pc) {
+  if (!common_flags()->dump_instruction_bytes || (pc < GetPageSizeCached()))
+    return;
+  InternalScopedString str(1024);
+  str.append("First 16 instruction bytes at pc: ");
+  if (IsAccessibleMemoryRange(pc, 16)) {
+    for (int i = 0; i < 16; ++i) {
+      PrintMemoryByte(&str, "", ((u8 *)pc)[i]);
+    }
+    str.append("\n");
+  } else {
+    str.append("unaccessible\n");
+  }
+  Report("%s", str.data());
+}
+
+static void MaybeDumpRegisters(void *context) {
+  if (!common_flags()->dump_registers) return;
+  SignalContext::DumpAllRegisters(context);
+}
+
+static void ReportStackOverflowImpl(const SignalContext &sig, u32 tid,
+                                    UnwindSignalStackCallbackType unwind,
+                                    const void *unwind_context) {
+  SanitizerCommonDecorator d;
+  Printf("%s", d.Warning());
+  static const char kDescription[] = "stack-overflow";
+  Report("ERROR: %s: %s on address %p (pc %p bp %p sp %p T%d)\n",
+         SanitizerToolName, kDescription, (void *)sig.addr, (void *)sig.pc,
+         (void *)sig.bp, (void *)sig.sp, tid);
+  Printf("%s", d.Default());
+  InternalMmapVector<BufferedStackTrace> stack_buffer(1);
+  BufferedStackTrace *stack = stack_buffer.data();
+  stack->Reset();
+  unwind(sig, unwind_context, stack);
+  stack->Print();
+  ReportErrorSummary(kDescription, stack);
+}
+
+static void ReportDeadlySignalImpl(const SignalContext &sig, u32 tid,
+                                   UnwindSignalStackCallbackType unwind,
+                                   const void *unwind_context) {
+  SanitizerCommonDecorator d;
+  Printf("%s", d.Warning());
+  const char *description = sig.Describe();
+  if (sig.is_memory_access && !sig.is_true_faulting_addr)
+    Report("ERROR: %s: %s on unknown address (pc %p bp %p sp %p T%d)\n",
+           SanitizerToolName, description, (void *)sig.pc, (void *)sig.bp,
+           (void *)sig.sp, tid);
+  else
+    Report("ERROR: %s: %s on unknown address %p (pc %p bp %p sp %p T%d)\n",
+           SanitizerToolName, description, (void *)sig.addr, (void *)sig.pc,
+           (void *)sig.bp, (void *)sig.sp, tid);
+  Printf("%s", d.Default());
+  if (sig.pc < GetPageSizeCached())
+    Report("Hint: pc points to the zero page.\n");
+  if (sig.is_memory_access) {
+    const char *access_type =
+        sig.write_flag == SignalContext::WRITE
+            ? "WRITE"
+            : (sig.write_flag == SignalContext::READ ? "READ" : "UNKNOWN");
+    Report("The signal is caused by a %s memory access.\n", access_type);
+    if (!sig.is_true_faulting_addr)
+      Report("Hint: this fault was caused by a dereference of a high value "
+             "address (see register values below).  Dissassemble the provided "
+             "pc to learn which register was used.\n");
+    else if (sig.addr < GetPageSizeCached())
+      Report("Hint: address points to the zero page.\n");
+  }
+  MaybeReportNonExecRegion(sig.pc);
+  InternalMmapVector<BufferedStackTrace> stack_buffer(1);
+  BufferedStackTrace *stack = stack_buffer.data();
+  stack->Reset();
+  unwind(sig, unwind_context, stack);
+  stack->Print();
+  MaybeDumpInstructionBytes(sig.pc);
+  MaybeDumpRegisters(sig.context);
+  Printf("%s can not provide additional info.\n", SanitizerToolName);
+  ReportErrorSummary(description, stack);
+}
+
+void ReportDeadlySignal(const SignalContext &sig, u32 tid,
+                        UnwindSignalStackCallbackType unwind,
+                        const void *unwind_context) {
+  if (sig.IsStackOverflow())
+    ReportStackOverflowImpl(sig, tid, unwind, unwind_context);
+  else
+    ReportDeadlySignalImpl(sig, tid, unwind, unwind_context);
+}
+
+void HandleDeadlySignal(void *siginfo, void *context, u32 tid,
+                        UnwindSignalStackCallbackType unwind,
+                        const void *unwind_context) {
+  StartReportDeadlySignal();
+  ScopedErrorReportLock rl;
+  SignalContext sig(siginfo, context);
+  ReportDeadlySignal(sig, tid, unwind, unwind_context);
+  Report("ABORTING\n");
+  Die();
+}
+
+#endif  // !SANITIZER_FUCHSIA && !SANITIZER_GO
+
+static atomic_uintptr_t reporting_thread = {0};
+static StaticSpinMutex CommonSanitizerReportMutex;
+
+ScopedErrorReportLock::ScopedErrorReportLock() {
+  uptr current = GetThreadSelf();
+  for (;;) {
+    uptr expected = 0;
+    if (atomic_compare_exchange_strong(&reporting_thread, &expected, current,
+                                       memory_order_relaxed)) {
+      // We've claimed reporting_thread so proceed.
+      CommonSanitizerReportMutex.Lock();
+      return;
+    }
+
+    if (expected == current) {
+      // This is either asynch signal or nested error during error reporting.
+      // Fail simple to avoid deadlocks in Report().
+
+      // Can't use Report() here because of potential deadlocks in nested
+      // signal handlers.
+      CatastrophicErrorWrite(SanitizerToolName,
+                             internal_strlen(SanitizerToolName));
+      static const char msg[] = ": nested bug in the same thread, aborting.\n";
+      CatastrophicErrorWrite(msg, sizeof(msg) - 1);
+
+      internal__exit(common_flags()->exitcode);
+    }
+
+    internal_sched_yield();
+  }
+}
+
+ScopedErrorReportLock::~ScopedErrorReportLock() {
+  CommonSanitizerReportMutex.Unlock();
+  atomic_store_relaxed(&reporting_thread, 0);
+}
+
+void ScopedErrorReportLock::CheckLocked() {
+  CommonSanitizerReportMutex.CheckLocked();
+}
+
+}  // namespace __sanitizer
diff --git a/lib/tsan/sanitizer_common/sanitizer_symbolizer_win.cpp b/lib/tsan/sanitizer_common/sanitizer_symbolizer_win.cpp
new file mode 100644
index 0000000000..373437e7ee
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_symbolizer_win.cpp
@@ -0,0 +1,318 @@
+//===-- sanitizer_symbolizer_win.cpp --------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries.
+// Windows-specific implementation of symbolizer parts.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_WINDOWS
+
+#include "sanitizer_dbghelp.h"
+#include "sanitizer_symbolizer_internal.h"
+
+namespace __sanitizer {
+
+decltype(::StackWalk64) *StackWalk64;
+decltype(::SymCleanup) *SymCleanup;
+decltype(::SymFromAddr) *SymFromAddr;
+decltype(::SymFunctionTableAccess64) *SymFunctionTableAccess64;
+decltype(::SymGetLineFromAddr64) *SymGetLineFromAddr64;
+decltype(::SymGetModuleBase64) *SymGetModuleBase64;
+decltype(::SymGetSearchPathW) *SymGetSearchPathW;
+decltype(::SymInitialize) *SymInitialize;
+decltype(::SymSetOptions) *SymSetOptions;
+decltype(::SymSetSearchPathW) *SymSetSearchPathW;
+decltype(::UnDecorateSymbolName) *UnDecorateSymbolName;
+
+namespace {
+
+class WinSymbolizerTool : public SymbolizerTool {
+ public:
+  // The constructor is provided to avoid synthesized memsets.
+  WinSymbolizerTool() {}
+
+  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override;
+  bool SymbolizeData(uptr addr, DataInfo *info) override {
+    return false;
+  }
+  const char *Demangle(const char *name) override;
+};
+
+bool is_dbghelp_initialized = false;
+
+bool TrySymInitialize() {
+  SymSetOptions(SYMOPT_DEFERRED_LOADS | SYMOPT_UNDNAME | SYMOPT_LOAD_LINES);
+  return SymInitialize(GetCurrentProcess(), 0, TRUE);
+  // FIXME: We don't call SymCleanup() on exit yet - should we?
+}
+
+}  // namespace
+
+// Initializes DbgHelp library, if it's not yet initialized. Calls to this
+// function should be synchronized with respect to other calls to DbgHelp API
+// (e.g. from WinSymbolizerTool).
+void InitializeDbgHelpIfNeeded() {
+  if (is_dbghelp_initialized)
+    return;
+
+  HMODULE dbghelp = LoadLibraryA("dbghelp.dll");
+  CHECK(dbghelp && "failed to load dbghelp.dll");
+
+#define DBGHELP_IMPORT(name)                                                  \
+  do {                                                                        \
+    name =                                                                    \
+        reinterpret_cast<decltype(::name) *>(GetProcAddress(dbghelp, #name)); \
+    CHECK(name != nullptr);                                                   \
+  } while (0)
+  DBGHELP_IMPORT(StackWalk64);
+  DBGHELP_IMPORT(SymCleanup);
+  DBGHELP_IMPORT(SymFromAddr);
+  DBGHELP_IMPORT(SymFunctionTableAccess64);
+  DBGHELP_IMPORT(SymGetLineFromAddr64);
+  DBGHELP_IMPORT(SymGetModuleBase64);
+  DBGHELP_IMPORT(SymGetSearchPathW);
+  DBGHELP_IMPORT(SymInitialize);
+  DBGHELP_IMPORT(SymSetOptions);
+  DBGHELP_IMPORT(SymSetSearchPathW);
+  DBGHELP_IMPORT(UnDecorateSymbolName);
+#undef DBGHELP_IMPORT
+
+  if (!TrySymInitialize()) {
+    // OK, maybe the client app has called SymInitialize already.
+    // That's a bit unfortunate for us as all the DbgHelp functions are
+    // single-threaded and we can't coordinate with the app.
+    // FIXME: Can we stop the other threads at this point?
+    // Anyways, we have to reconfigure stuff to make sure that SymInitialize
+    // has all the appropriate options set.
+    // Cross our fingers and reinitialize DbgHelp.
+    Report("*** WARNING: Failed to initialize DbgHelp!              ***\n");
+    Report("*** Most likely this means that the app is already      ***\n");
+    Report("*** using DbgHelp, possibly with incompatible flags.    ***\n");
+    Report("*** Due to technical reasons, symbolization might crash ***\n");
+    Report("*** or produce wrong results.                           ***\n");
+    SymCleanup(GetCurrentProcess());
+    TrySymInitialize();
+  }
+  is_dbghelp_initialized = true;
+
+  // When an executable is run from a location different from the one where it
+  // was originally built, we may not see the nearby PDB files.
+  // To work around this, let's append the directory of the main module
+  // to the symbol search path.  All the failures below are not fatal.
+  const size_t kSymPathSize = 2048;
+  static wchar_t path_buffer[kSymPathSize + 1 + MAX_PATH];
+  if (!SymGetSearchPathW(GetCurrentProcess(), path_buffer, kSymPathSize)) {
+    Report("*** WARNING: Failed to SymGetSearchPathW ***\n");
+    return;
+  }
+  size_t sz = wcslen(path_buffer);
+  if (sz) {
+    CHECK_EQ(0, wcscat_s(path_buffer, L";"));
+    sz++;
+  }
+  DWORD res = GetModuleFileNameW(NULL, path_buffer + sz, MAX_PATH);
+  if (res == 0 || res == MAX_PATH) {
+    Report("*** WARNING: Failed to getting the EXE directory ***\n");
+    return;
+  }
+  // Write the zero character in place of the last backslash to get the
+  // directory of the main module at the end of path_buffer.
+  wchar_t *last_bslash = wcsrchr(path_buffer + sz, L'\\');
+  CHECK_NE(last_bslash, 0);
+  *last_bslash = L'\0';
+  if (!SymSetSearchPathW(GetCurrentProcess(), path_buffer)) {
+    Report("*** WARNING: Failed to SymSetSearchPathW\n");
+    return;
+  }
+}
+
+bool WinSymbolizerTool::SymbolizePC(uptr addr, SymbolizedStack *frame) {
+  InitializeDbgHelpIfNeeded();
+
+  // See http://msdn.microsoft.com/en-us/library/ms680578(VS.85).aspx
+  char buffer[sizeof(SYMBOL_INFO) + MAX_SYM_NAME * sizeof(CHAR)];
+  PSYMBOL_INFO symbol = (PSYMBOL_INFO)buffer;
+  symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
+  symbol->MaxNameLen = MAX_SYM_NAME;
+  DWORD64 offset = 0;
+  BOOL got_objname = SymFromAddr(GetCurrentProcess(),
+                                 (DWORD64)addr, &offset, symbol);
+  if (!got_objname)
+    return false;
+
+  DWORD unused;
+  IMAGEHLP_LINE64 line_info;
+  line_info.SizeOfStruct = sizeof(IMAGEHLP_LINE64);
+  BOOL got_fileline = SymGetLineFromAddr64(GetCurrentProcess(), (DWORD64)addr,
+                                           &unused, &line_info);
+  frame->info.function = internal_strdup(symbol->Name);
+  frame->info.function_offset = (uptr)offset;
+  if (got_fileline) {
+    frame->info.file = internal_strdup(line_info.FileName);
+    frame->info.line = line_info.LineNumber;
+  }
+  // Only consider this a successful symbolization attempt if we got file info.
+  // Otherwise, try llvm-symbolizer.
+  return got_fileline;
+}
+
+const char *WinSymbolizerTool::Demangle(const char *name) {
+  CHECK(is_dbghelp_initialized);
+  static char demangle_buffer[1000];
+  if (name[0] == '\01' &&
+      UnDecorateSymbolName(name + 1, demangle_buffer, sizeof(demangle_buffer),
+                           UNDNAME_NAME_ONLY))
+    return demangle_buffer;
+  else
+    return name;
+}
+
+const char *Symbolizer::PlatformDemangle(const char *name) {
+  return name;
+}
+
+namespace {
+struct ScopedHandle {
+  ScopedHandle() : h_(nullptr) {}
+  explicit ScopedHandle(HANDLE h) : h_(h) {}
+  ~ScopedHandle() {
+    if (h_)
+      ::CloseHandle(h_);
+  }
+  HANDLE get() { return h_; }
+  HANDLE *receive() { return &h_; }
+  HANDLE release() {
+    HANDLE h = h_;
+    h_ = nullptr;
+    return h;
+  }
+  HANDLE h_;
+};
+} // namespace
+
+bool SymbolizerProcess::StartSymbolizerSubprocess() {
+  // Create inherited pipes for stdin and stdout.
+  ScopedHandle stdin_read, stdin_write;
+  ScopedHandle stdout_read, stdout_write;
+  SECURITY_ATTRIBUTES attrs;
+  attrs.nLength = sizeof(SECURITY_ATTRIBUTES);
+  attrs.bInheritHandle = TRUE;
+  attrs.lpSecurityDescriptor = nullptr;
+  if (!::CreatePipe(stdin_read.receive(), stdin_write.receive(), &attrs, 0) ||
+      !::CreatePipe(stdout_read.receive(), stdout_write.receive(), &attrs, 0)) {
+    VReport(2, "WARNING: %s CreatePipe failed (error code: %d)\n",
+            SanitizerToolName, path_, GetLastError());
+    return false;
+  }
+
+  // Don't inherit the writing end of stdin or the reading end of stdout.
+  if (!SetHandleInformation(stdin_write.get(), HANDLE_FLAG_INHERIT, 0) ||
+      !SetHandleInformation(stdout_read.get(), HANDLE_FLAG_INHERIT, 0)) {
+    VReport(2, "WARNING: %s SetHandleInformation failed (error code: %d)\n",
+            SanitizerToolName, path_, GetLastError());
+    return false;
+  }
+
+  // Compute the command line. Wrap double quotes around everything.
+  const char *argv[kArgVMax];
+  GetArgV(path_, argv);
+  InternalScopedString command_line(kMaxPathLength * 3);
+  for (int i = 0; argv[i]; i++) {
+    const char *arg = argv[i];
+    int arglen = internal_strlen(arg);
+    // Check that tool command lines are simple and that complete escaping is
+    // unnecessary.
+    CHECK(!internal_strchr(arg, '"') && "quotes in args unsupported");
+    CHECK(!internal_strstr(arg, "\\\\") &&
+          "double backslashes in args unsupported");
+    CHECK(arglen > 0 && arg[arglen - 1] != '\\' &&
+          "args ending in backslash and empty args unsupported");
+    command_line.append("\"%s\" ", arg);
+  }
+  VReport(3, "Launching symbolizer command: %s\n", command_line.data());
+
+  // Launch llvm-symbolizer with stdin and stdout redirected.
+  STARTUPINFOA si;
+  memset(&si, 0, sizeof(si));
+  si.cb = sizeof(si);
+  si.dwFlags |= STARTF_USESTDHANDLES;
+  si.hStdInput = stdin_read.get();
+  si.hStdOutput = stdout_write.get();
+  PROCESS_INFORMATION pi;
+  memset(&pi, 0, sizeof(pi));
+  if (!CreateProcessA(path_,               // Executable
+                      command_line.data(), // Command line
+                      nullptr,             // Process handle not inheritable
+                      nullptr,             // Thread handle not inheritable
+                      TRUE,                // Set handle inheritance to TRUE
+                      0,                   // Creation flags
+                      nullptr,             // Use parent's environment block
+                      nullptr,             // Use parent's starting directory
+                      &si, &pi)) {
+    VReport(2, "WARNING: %s failed to create process for %s (error code: %d)\n",
+            SanitizerToolName, path_, GetLastError());
+    return false;
+  }
+
+  // Process creation succeeded, so transfer handle ownership into the fields.
+  input_fd_ = stdout_read.release();
+  output_fd_ = stdin_write.release();
+
+  // The llvm-symbolizer process is responsible for quitting itself when the
+  // stdin pipe is closed, so we don't need these handles. Close them to prevent
+  // leaks. If we ever want to try to kill the symbolizer process from the
+  // parent, we'll want to hang on to these handles.
+  CloseHandle(pi.hProcess);
+  CloseHandle(pi.hThread);
+  return true;
+}
+
+static void ChooseSymbolizerTools(IntrusiveList<SymbolizerTool> *list,
+                                  LowLevelAllocator *allocator) {
+  if (!common_flags()->symbolize) {
+    VReport(2, "Symbolizer is disabled.\n");
+    return;
+  }
+
+  // Add llvm-symbolizer in case the binary has dwarf.
+  const char *user_path = common_flags()->external_symbolizer_path;
+  const char *path =
+      user_path ? user_path : FindPathToBinary("llvm-symbolizer.exe");
+  if (path) {
+    VReport(2, "Using llvm-symbolizer at %spath: %s\n",
+            user_path ? "user-specified " : "", path);
+    list->push_back(new(*allocator) LLVMSymbolizer(path, allocator));
+  } else {
+    if (user_path && user_path[0] == '\0') {
+      VReport(2, "External symbolizer is explicitly disabled.\n");
+    } else {
+      VReport(2, "External symbolizer is not present.\n");
+    }
+  }
+
+  // Add the dbghelp based symbolizer.
+  list->push_back(new(*allocator) WinSymbolizerTool());
+}
+
+Symbolizer *Symbolizer::PlatformInit() {
+  IntrusiveList<SymbolizerTool> list;
+  list.clear();
+  ChooseSymbolizerTools(&list, &symbolizer_allocator_);
+
+  return new(symbolizer_allocator_) Symbolizer(list);
+}
+
+void Symbolizer::LateInitialize() {
+  Symbolizer::GetOrInit()->LateInitializeTools();
+}
+
+}  // namespace __sanitizer
+
+#endif  // _WIN32
diff --git a/lib/tsan/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp b/lib/tsan/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp
new file mode 100644
index 0000000000..b2628dcc4d
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp
@@ -0,0 +1,180 @@
+//===-- sanitizer_unwind_linux_libcdep.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the unwind.h-based (aka "slow") stack unwinding routines
+// available to the tools on Linux, Android, NetBSD, FreeBSD, and Solaris.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
+    SANITIZER_SOLARIS
+#include "sanitizer_common.h"
+#include "sanitizer_stacktrace.h"
+
+#if SANITIZER_ANDROID
+#include <dlfcn.h>  // for dlopen()
+#endif
+
+#if SANITIZER_FREEBSD
+#define _GNU_SOURCE  // to declare _Unwind_Backtrace() from <unwind.h>
+#endif
+#include <unwind.h>
+
+namespace __sanitizer {
+
+namespace {
+
+//---------------------------- UnwindSlow --------------------------------------
+
+typedef struct {
+  uptr absolute_pc;
+  uptr stack_top;
+  uptr stack_size;
+} backtrace_frame_t;
+
+extern "C" {
+typedef void *(*acquire_my_map_info_list_func)();
+typedef void (*release_my_map_info_list_func)(void *map);
+typedef sptr (*unwind_backtrace_signal_arch_func)(
+    void *siginfo, void *sigcontext, void *map_info_list,
+    backtrace_frame_t *backtrace, uptr ignore_depth, uptr max_depth);
+acquire_my_map_info_list_func acquire_my_map_info_list;
+release_my_map_info_list_func release_my_map_info_list;
+unwind_backtrace_signal_arch_func unwind_backtrace_signal_arch;
+} // extern "C"
+
+#if defined(__arm__) && !SANITIZER_NETBSD
+// NetBSD uses dwarf EH
+#define UNWIND_STOP _URC_END_OF_STACK
+#define UNWIND_CONTINUE _URC_NO_REASON
+#else
+#define UNWIND_STOP _URC_NORMAL_STOP
+#define UNWIND_CONTINUE _URC_NO_REASON
+#endif
+
+uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
+#if defined(__arm__) && !SANITIZER_MAC
+  uptr val;
+  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
+      15 /* r15 = PC */, _UVRSD_UINT32, &val);
+  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
+  // Clear the Thumb bit.
+  return val & ~(uptr)1;
+#else
+  return (uptr)_Unwind_GetIP(ctx);
+#endif
+}
+
+struct UnwindTraceArg {
+  BufferedStackTrace *stack;
+  u32 max_depth;
+};
+
+_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
+  UnwindTraceArg *arg = (UnwindTraceArg*)param;
+  CHECK_LT(arg->stack->size, arg->max_depth);
+  uptr pc = Unwind_GetIP(ctx);
+  const uptr kPageSize = GetPageSizeCached();
+  // Let's assume that any pointer in the 0th page (i.e. <0x1000 on i386 and
+  // x86_64) is invalid and stop unwinding here.  If we're adding support for
+  // a platform where this isn't true, we need to reconsider this check.
+  if (pc < kPageSize) return UNWIND_STOP;
+  arg->stack->trace_buffer[arg->stack->size++] = pc;
+  if (arg->stack->size == arg->max_depth) return UNWIND_STOP;
+  return UNWIND_CONTINUE;
+}
+
+}  // namespace
+
+#if SANITIZER_ANDROID
+void SanitizerInitializeUnwinder() {
+  if (AndroidGetApiLevel() >= ANDROID_LOLLIPOP_MR1) return;
+
+  // Pre-lollipop Android can not unwind through signal handler frames with
+  // libgcc unwinder, but it has a libcorkscrew.so library with the necessary
+  // workarounds.
+  void *p = dlopen("libcorkscrew.so", RTLD_LAZY);
+  if (!p) {
+    VReport(1,
+            "Failed to open libcorkscrew.so. You may see broken stack traces "
+            "in SEGV reports.");
+    return;
+  }
+  acquire_my_map_info_list =
+      (acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list");
+  release_my_map_info_list =
+      (release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list");
+  unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym(
+      p, "unwind_backtrace_signal_arch");
+  if (!acquire_my_map_info_list || !release_my_map_info_list ||
+      !unwind_backtrace_signal_arch) {
+    VReport(1,
+            "Failed to find one of the required symbols in libcorkscrew.so. "
+            "You may see broken stack traces in SEGV reports.");
+    acquire_my_map_info_list = 0;
+    unwind_backtrace_signal_arch = 0;
+    release_my_map_info_list = 0;
+  }
+}
+#endif
+
+void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
+  CHECK_GE(max_depth, 2);
+  size = 0;
+  UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
+  _Unwind_Backtrace(Unwind_Trace, &arg);
+  // We need to pop a few frames so that pc is on top.
+  uptr to_pop = LocatePcInTrace(pc);
+  // trace_buffer[0] belongs to the current function so we always pop it,
+  // unless there is only 1 frame in the stack trace (1 frame is always better
+  // than 0!).
+  // 1-frame stacks don't normally happen, but this depends on the actual
+  // unwinder implementation (libgcc, libunwind, etc) which is outside of our
+  // control.
+  if (to_pop == 0 && size > 1)
+    to_pop = 1;
+  PopStackFrames(to_pop);
+#if defined(__GNUC__) && defined(__sparc__)
+  // __builtin_return_address returns the address of the call instruction
+  // on the SPARC and not the return address, so we need to compensate.
+  trace_buffer[0] = GetNextInstructionPc(pc);
+#else
+  trace_buffer[0] = pc;
+#endif
+}
+
+void BufferedStackTrace::UnwindSlow(uptr pc, void *context, u32 max_depth) {
+  CHECK(context);
+  CHECK_GE(max_depth, 2);
+  if (!unwind_backtrace_signal_arch) {
+    UnwindSlow(pc, max_depth);
+    return;
+  }
+
+  void *map = acquire_my_map_info_list();
+  CHECK(map);
+  InternalMmapVector<backtrace_frame_t> frames(kStackTraceMax);
+  // siginfo argument appears to be unused.
+  sptr res = unwind_backtrace_signal_arch(/* siginfo */ 0, context, map,
+                                          frames.data(),
+                                          /* ignore_depth */ 0, max_depth);
+  release_my_map_info_list(map);
+  if (res < 0) return;
+  CHECK_LE((uptr)res, kStackTraceMax);
+
+  size = 0;
+  // +2 compensate for libcorkscrew unwinder returning addresses of call
+  // instructions instead of raw return addresses.
+  for (sptr i = 0; i < res; ++i)
+    trace_buffer[size++] = frames[i].absolute_pc + 2;
+}
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||
+        // SANITIZER_SOLARIS
diff --git a/lib/tsan/sanitizer_common/sanitizer_unwind_win.cpp b/lib/tsan/sanitizer_common/sanitizer_unwind_win.cpp
new file mode 100644
index 0000000000..8e06940685
--- /dev/null
+++ b/lib/tsan/sanitizer_common/sanitizer_unwind_win.cpp
@@ -0,0 +1,75 @@
+//===-- sanitizer_unwind_win.cpp ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// Sanitizer unwind Windows specific functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_WINDOWS
+
+#define WIN32_LEAN_AND_MEAN
+#define NOGDI
+#include <windows.h>
+
+#include "sanitizer_dbghelp.h"  // for StackWalk64
+#include "sanitizer_stacktrace.h"
+#include "sanitizer_symbolizer.h"  // for InitializeDbgHelpIfNeeded
+
+using namespace __sanitizer;
+
+#if !SANITIZER_GO
+void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
+  CHECK_GE(max_depth, 2);
+  // FIXME: CaptureStackBackTrace might be too slow for us.
+  // FIXME: Compare with StackWalk64.
+  // FIXME: Look at LLVMUnhandledExceptionFilter in Signals.inc
+  size = CaptureStackBackTrace(1, Min(max_depth, kStackTraceMax),
+    (void **)&trace_buffer[0], 0);
+  if (size == 0)
+    return;
+
+  // Skip the RTL frames by searching for the PC in the stacktrace.
+  uptr pc_location = LocatePcInTrace(pc);
+  PopStackFrames(pc_location);
+}
+
+void BufferedStackTrace::UnwindSlow(uptr pc, void *context, u32 max_depth) {
+  CHECK(context);
+  CHECK_GE(max_depth, 2);
+  CONTEXT ctx = *(CONTEXT *)context;
+  STACKFRAME64 stack_frame;
+  memset(&stack_frame, 0, sizeof(stack_frame));
+
+  InitializeDbgHelpIfNeeded();
+
+  size = 0;
+#if defined(_WIN64)
+  int machine_type = IMAGE_FILE_MACHINE_AMD64;
+  stack_frame.AddrPC.Offset = ctx.Rip;
+  stack_frame.AddrFrame.Offset = ctx.Rbp;
+  stack_frame.AddrStack.Offset = ctx.Rsp;
+#else
+  int machine_type = IMAGE_FILE_MACHINE_I386;
+  stack_frame.AddrPC.Offset = ctx.Eip;
+  stack_frame.AddrFrame.Offset = ctx.Ebp;
+  stack_frame.AddrStack.Offset = ctx.Esp;
+#endif
+  stack_frame.AddrPC.Mode = AddrModeFlat;
+  stack_frame.AddrFrame.Mode = AddrModeFlat;
+  stack_frame.AddrStack.Mode = AddrModeFlat;
+  while (StackWalk64(machine_type, GetCurrentProcess(), GetCurrentThread(),
+    &stack_frame, &ctx, NULL, SymFunctionTableAccess64,
+    SymGetModuleBase64, NULL) &&
+    size < Min(max_depth, kStackTraceMax)) {
+    trace_buffer[size++] = (uptr)stack_frame.AddrPC.Offset;
+  }
+}
+#endif  // #if !SANITIZER_GO
+
+#endif  // SANITIZER_WINDOWS
diff --git a/lib/tsan/tsan_interceptors_mac.cpp b/lib/tsan/tsan_interceptors_mac.cpp
new file mode 100644
index 0000000000..aa29536d86
--- /dev/null
+++ b/lib/tsan/tsan_interceptors_mac.cpp
@@ -0,0 +1,519 @@
+//===-- tsan_interceptors_mac.cpp -----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of ThreadSanitizer (TSan), a race detector.
+//
+// Mac-specific interceptors.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_platform.h"
+#if SANITIZER_MAC
+
+#include "interception/interception.h"
+#include "tsan_interceptors.h"
+#include "tsan_interface.h"
+#include "tsan_interface_ann.h"
+#include "sanitizer_common/sanitizer_addrhashmap.h"
+
+#include <errno.h>
+#include <libkern/OSAtomic.h>
+#include <objc/objc-sync.h>
+#include <os/lock.h>
+#include <sys/ucontext.h>
+
+#if defined(__has_include) && __has_include(<xpc/xpc.h>)
+#include <xpc/xpc.h>
+#endif  // #if defined(__has_include) && __has_include(<xpc/xpc.h>)
+
+typedef long long_t;
+
+extern "C" {
+int getcontext(ucontext_t *ucp) __attribute__((returns_twice));
+int setcontext(const ucontext_t *ucp);
+}
+
+namespace __tsan {
+
+// The non-barrier versions of OSAtomic* functions are semantically mo_relaxed,
+// but the two variants (e.g. OSAtomicAdd32 and OSAtomicAdd32Barrier) are
+// actually aliases of each other, and we cannot have different interceptors for
+// them, because they're actually the same function.  Thus, we have to stay
+// conservative and treat the non-barrier versions as mo_acq_rel.
+static const morder kMacOrderBarrier = mo_acq_rel;
+static const morder kMacOrderNonBarrier = mo_acq_rel;
+
+#define OSATOMIC_INTERCEPTOR(return_t, t, tsan_t, f, tsan_atomic_f, mo) \
+  TSAN_INTERCEPTOR(return_t, f, t x, volatile t *ptr) {                 \
+    SCOPED_TSAN_INTERCEPTOR(f, x, ptr);                                 \
+    return tsan_atomic_f((volatile tsan_t *)ptr, x, mo);                \
+  }
+
+#define OSATOMIC_INTERCEPTOR_PLUS_X(return_t, t, tsan_t, f, tsan_atomic_f, mo) \
+  TSAN_INTERCEPTOR(return_t, f, t x, volatile t *ptr) {                        \
+    SCOPED_TSAN_INTERCEPTOR(f, x, ptr);                                        \
+    return tsan_atomic_f((volatile tsan_t *)ptr, x, mo) + x;                   \
+  }
+
+#define OSATOMIC_INTERCEPTOR_PLUS_1(return_t, t, tsan_t, f, tsan_atomic_f, mo) \
+  TSAN_INTERCEPTOR(return_t, f, volatile t *ptr) {                             \
+    SCOPED_TSAN_INTERCEPTOR(f, ptr);                                           \
+    return tsan_atomic_f((volatile tsan_t *)ptr, 1, mo) + 1;                   \
+  }
+
+#define OSATOMIC_INTERCEPTOR_MINUS_1(return_t, t, tsan_t, f, tsan_atomic_f, \
+                                     mo)                                    \
+  TSAN_INTERCEPTOR(return_t, f, volatile t *ptr) {                          \
+    SCOPED_TSAN_INTERCEPTOR(f, ptr);                                        \
+    return tsan_atomic_f((volatile tsan_t *)ptr, 1, mo) - 1;                \
+  }
+
+#define OSATOMIC_INTERCEPTORS_ARITHMETIC(f, tsan_atomic_f, m)                  \
+  m(int32_t, int32_t, a32, f##32, __tsan_atomic32_##tsan_atomic_f,             \
+    kMacOrderNonBarrier)                                                       \
+  m(int32_t, int32_t, a32, f##32##Barrier, __tsan_atomic32_##tsan_atomic_f,    \
+    kMacOrderBarrier)                                                          \
+  m(int64_t, int64_t, a64, f##64, __tsan_atomic64_##tsan_atomic_f,             \
+    kMacOrderNonBarrier)                                                       \
+  m(int64_t, int64_t, a64, f##64##Barrier, __tsan_atomic64_##tsan_atomic_f,    \
+    kMacOrderBarrier)
+
+#define OSATOMIC_INTERCEPTORS_BITWISE(f, tsan_atomic_f, m, m_orig)             \
+  m(int32_t, uint32_t, a32, f##32, __tsan_atomic32_##tsan_atomic_f,            \
+    kMacOrderNonBarrier)                                                       \
+  m(int32_t, uint32_t, a32, f##32##Barrier, __tsan_atomic32_##tsan_atomic_f,   \
+    kMacOrderBarrier)                                                          \
+  m_orig(int32_t, uint32_t, a32, f##32##Orig, __tsan_atomic32_##tsan_atomic_f, \
+    kMacOrderNonBarrier)                                                       \
+  m_orig(int32_t, uint32_t, a32, f##32##OrigBarrier,                           \
+    __tsan_atomic32_##tsan_atomic_f, kMacOrderBarrier)
+
+OSATOMIC_INTERCEPTORS_ARITHMETIC(OSAtomicAdd, fetch_add,
+                                 OSATOMIC_INTERCEPTOR_PLUS_X)
+OSATOMIC_INTERCEPTORS_ARITHMETIC(OSAtomicIncrement, fetch_add,
+                                 OSATOMIC_INTERCEPTOR_PLUS_1)
+OSATOMIC_INTERCEPTORS_ARITHMETIC(OSAtomicDecrement, fetch_sub,
+                                 OSATOMIC_INTERCEPTOR_MINUS_1)
+OSATOMIC_INTERCEPTORS_BITWISE(OSAtomicOr, fetch_or, OSATOMIC_INTERCEPTOR_PLUS_X,
+                              OSATOMIC_INTERCEPTOR)
+OSATOMIC_INTERCEPTORS_BITWISE(OSAtomicAnd, fetch_and,
+                              OSATOMIC_INTERCEPTOR_PLUS_X, OSATOMIC_INTERCEPTOR)
+OSATOMIC_INTERCEPTORS_BITWISE(OSAtomicXor, fetch_xor,
+                              OSATOMIC_INTERCEPTOR_PLUS_X, OSATOMIC_INTERCEPTOR)
+
+#define OSATOMIC_INTERCEPTORS_CAS(f, tsan_atomic_f, tsan_t, t)              \
+  TSAN_INTERCEPTOR(bool, f, t old_value, t new_value, t volatile *ptr) {    \
+    SCOPED_TSAN_INTERCEPTOR(f, old_value, new_value, ptr);                  \
+    return tsan_atomic_f##_compare_exchange_strong(                         \
+        (volatile tsan_t *)ptr, (tsan_t *)&old_value, (tsan_t)new_value,    \
+        kMacOrderNonBarrier, kMacOrderNonBarrier);                          \
+  }                                                                         \
+                                                                            \
+  TSAN_INTERCEPTOR(bool, f##Barrier, t old_value, t new_value,              \
+                   t volatile *ptr) {                                       \
+    SCOPED_TSAN_INTERCEPTOR(f##Barrier, old_value, new_value, ptr);         \
+    return tsan_atomic_f##_compare_exchange_strong(                         \
+        (volatile tsan_t *)ptr, (tsan_t *)&old_value, (tsan_t)new_value,    \
+        kMacOrderBarrier, kMacOrderNonBarrier);                             \
+  }
+
+OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwapInt, __tsan_atomic32, a32, int)
+OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwapLong, __tsan_atomic64, a64,
+                          long_t)
+OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwapPtr, __tsan_atomic64, a64,
+                          void *)
+OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwap32, __tsan_atomic32, a32,
+                          int32_t)
+OSATOMIC_INTERCEPTORS_CAS(OSAtomicCompareAndSwap64, __tsan_atomic64, a64,
+                          int64_t)
+
+#define OSATOMIC_INTERCEPTOR_BITOP(f, op, clear, mo)             \
+  TSAN_INTERCEPTOR(bool, f, uint32_t n, volatile void *ptr) {    \
+    SCOPED_TSAN_INTERCEPTOR(f, n, ptr);                          \
+    volatile char *byte_ptr = ((volatile char *)ptr) + (n >> 3); \
+    char bit = 0x80u >> (n & 7);                                 \
+    char mask = clear ? ~bit : bit;                              \
+    char orig_byte = op((volatile a8 *)byte_ptr, mask, mo);      \
+    return orig_byte & bit;                                      \
+  }
+
+#define OSATOMIC_INTERCEPTORS_BITOP(f, op, clear)               \
+  OSATOMIC_INTERCEPTOR_BITOP(f, op, clear, kMacOrderNonBarrier) \
+  OSATOMIC_INTERCEPTOR_BITOP(f##Barrier, op, clear, kMacOrderBarrier)
+
+OSATOMIC_INTERCEPTORS_BITOP(OSAtomicTestAndSet, __tsan_atomic8_fetch_or, false)
+OSATOMIC_INTERCEPTORS_BITOP(OSAtomicTestAndClear, __tsan_atomic8_fetch_and,
+                            true)
+
+TSAN_INTERCEPTOR(void, OSAtomicEnqueue, OSQueueHead *list, void *item,
+                 size_t offset) {
+  SCOPED_TSAN_INTERCEPTOR(OSAtomicEnqueue, list, item, offset);
+  __tsan_release(item);
+  REAL(OSAtomicEnqueue)(list, item, offset);
+}
+
+TSAN_INTERCEPTOR(void *, OSAtomicDequeue, OSQueueHead *list, size_t offset) {
+  SCOPED_TSAN_INTERCEPTOR(OSAtomicDequeue, list, offset);
+  void *item = REAL(OSAtomicDequeue)(list, offset);
+  if (item) __tsan_acquire(item);
+  return item;
+}
+
+// OSAtomicFifoEnqueue and OSAtomicFifoDequeue are only on OS X.
+#if !SANITIZER_IOS
+
+TSAN_INTERCEPTOR(void, OSAtomicFifoEnqueue, OSFifoQueueHead *list, void *item,
+                 size_t offset) {
+  SCOPED_TSAN_INTERCEPTOR(OSAtomicFifoEnqueue, list, item, offset);
+  __tsan_release(item);
+  REAL(OSAtomicFifoEnqueue)(list, item, offset);
+}
+
+TSAN_INTERCEPTOR(void *, OSAtomicFifoDequeue, OSFifoQueueHead *list,
+                 size_t offset) {
+  SCOPED_TSAN_INTERCEPTOR(OSAtomicFifoDequeue, list, offset);
+  void *item = REAL(OSAtomicFifoDequeue)(list, offset);
+  if (item) __tsan_acquire(item);
+  return item;
+}
+
+#endif
+
+TSAN_INTERCEPTOR(void, OSSpinLockLock, volatile OSSpinLock *lock) {
+  CHECK(!cur_thread()->is_dead);
+  if (!cur_thread()->is_inited) {
+    return REAL(OSSpinLockLock)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(OSSpinLockLock, lock);
+  REAL(OSSpinLockLock)(lock);
+  Acquire(thr, pc, (uptr)lock);
+}
+
+TSAN_INTERCEPTOR(bool, OSSpinLockTry, volatile OSSpinLock *lock) {
+  CHECK(!cur_thread()->is_dead);
+  if (!cur_thread()->is_inited) {
+    return REAL(OSSpinLockTry)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(OSSpinLockTry, lock);
+  bool result = REAL(OSSpinLockTry)(lock);
+  if (result)
+    Acquire(thr, pc, (uptr)lock);
+  return result;
+}
+
+TSAN_INTERCEPTOR(void, OSSpinLockUnlock, volatile OSSpinLock *lock) {
+  CHECK(!cur_thread()->is_dead);
+  if (!cur_thread()->is_inited) {
+    return REAL(OSSpinLockUnlock)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(OSSpinLockUnlock, lock);
+  Release(thr, pc, (uptr)lock);
+  REAL(OSSpinLockUnlock)(lock);
+}
+
+TSAN_INTERCEPTOR(void, os_lock_lock, void *lock) {
+  CHECK(!cur_thread()->is_dead);
+  if (!cur_thread()->is_inited) {
+    return REAL(os_lock_lock)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(os_lock_lock, lock);
+  REAL(os_lock_lock)(lock);
+  Acquire(thr, pc, (uptr)lock);
+}
+
+TSAN_INTERCEPTOR(bool, os_lock_trylock, void *lock) {
+  CHECK(!cur_thread()->is_dead);
+  if (!cur_thread()->is_inited) {
+    return REAL(os_lock_trylock)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(os_lock_trylock, lock);
+  bool result = REAL(os_lock_trylock)(lock);
+  if (result)
+    Acquire(thr, pc, (uptr)lock);
+  return result;
+}
+
+TSAN_INTERCEPTOR(void, os_lock_unlock, void *lock) {
+  CHECK(!cur_thread()->is_dead);
+  if (!cur_thread()->is_inited) {
+    return REAL(os_lock_unlock)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(os_lock_unlock, lock);
+  Release(thr, pc, (uptr)lock);
+  REAL(os_lock_unlock)(lock);
+}
+
+TSAN_INTERCEPTOR(void, os_unfair_lock_lock, os_unfair_lock_t lock) {
+  if (!cur_thread()->is_inited || cur_thread()->is_dead) {
+    return REAL(os_unfair_lock_lock)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(os_unfair_lock_lock, lock);
+  REAL(os_unfair_lock_lock)(lock);
+  Acquire(thr, pc, (uptr)lock);
+}
+
+TSAN_INTERCEPTOR(void, os_unfair_lock_lock_with_options, os_unfair_lock_t lock,
+                 u32 options) {
+  if (!cur_thread()->is_inited || cur_thread()->is_dead) {
+    return REAL(os_unfair_lock_lock_with_options)(lock, options);
+  }
+  SCOPED_TSAN_INTERCEPTOR(os_unfair_lock_lock_with_options, lock, options);
+  REAL(os_unfair_lock_lock_with_options)(lock, options);
+  Acquire(thr, pc, (uptr)lock);
+}
+
+TSAN_INTERCEPTOR(bool, os_unfair_lock_trylock, os_unfair_lock_t lock) {
+  if (!cur_thread()->is_inited || cur_thread()->is_dead) {
+    return REAL(os_unfair_lock_trylock)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(os_unfair_lock_trylock, lock);
+  bool result = REAL(os_unfair_lock_trylock)(lock);
+  if (result)
+    Acquire(thr, pc, (uptr)lock);
+  return result;
+}
+
+TSAN_INTERCEPTOR(void, os_unfair_lock_unlock, os_unfair_lock_t lock) {
+  if (!cur_thread()->is_inited || cur_thread()->is_dead) {
+    return REAL(os_unfair_lock_unlock)(lock);
+  }
+  SCOPED_TSAN_INTERCEPTOR(os_unfair_lock_unlock, lock);
+  Release(thr, pc, (uptr)lock);
+  REAL(os_unfair_lock_unlock)(lock);
+}
+
+#if defined(__has_include) && __has_include(<xpc/xpc.h>)
+
+TSAN_INTERCEPTOR(void, xpc_connection_set_event_handler,
+                 xpc_connection_t connection, xpc_handler_t handler) {
+  SCOPED_TSAN_INTERCEPTOR(xpc_connection_set_event_handler, connection,
+                          handler);
+  Release(thr, pc, (uptr)connection);
+  xpc_handler_t new_handler = ^(xpc_object_t object) {
+    {
+      SCOPED_INTERCEPTOR_RAW(xpc_connection_set_event_handler);
+      Acquire(thr, pc, (uptr)connection);
+    }
+    handler(object);
+  };
+  REAL(xpc_connection_set_event_handler)(connection, new_handler);
+}
+
+TSAN_INTERCEPTOR(void, xpc_connection_send_barrier, xpc_connection_t connection,
+                 dispatch_block_t barrier) {
+  SCOPED_TSAN_INTERCEPTOR(xpc_connection_send_barrier, connection, barrier);
+  Release(thr, pc, (uptr)connection);
+  dispatch_block_t new_barrier = ^() {
+    {
+      SCOPED_INTERCEPTOR_RAW(xpc_connection_send_barrier);
+      Acquire(thr, pc, (uptr)connection);
+    }
+    barrier();
+  };
+  REAL(xpc_connection_send_barrier)(connection, new_barrier);
+}
+
+TSAN_INTERCEPTOR(void, xpc_connection_send_message_with_reply,
+                 xpc_connection_t connection, xpc_object_t message,
+                 dispatch_queue_t replyq, xpc_handler_t handler) {
+  SCOPED_TSAN_INTERCEPTOR(xpc_connection_send_message_with_reply, connection,
+                          message, replyq, handler);
+  Release(thr, pc, (uptr)connection);
+  xpc_handler_t new_handler = ^(xpc_object_t object) {
+    {
+      SCOPED_INTERCEPTOR_RAW(xpc_connection_send_message_with_reply);
+      Acquire(thr, pc, (uptr)connection);
+    }
+    handler(object);
+  };
+  REAL(xpc_connection_send_message_with_reply)
+  (connection, message, replyq, new_handler);
+}
+
+TSAN_INTERCEPTOR(void, xpc_connection_cancel, xpc_connection_t connection) {
+  SCOPED_TSAN_INTERCEPTOR(xpc_connection_cancel, connection);
+  Release(thr, pc, (uptr)connection);
+  REAL(xpc_connection_cancel)(connection);
+}
+
+#endif  // #if defined(__has_include) && __has_include(<xpc/xpc.h>)
+
+// Determines whether the Obj-C object pointer is a tagged pointer. Tagged
+// pointers encode the object data directly in their pointer bits and do not
+// have an associated memory allocation. The Obj-C runtime uses tagged pointers
+// to transparently optimize small objects.
+static bool IsTaggedObjCPointer(id obj) {
+  const uptr kPossibleTaggedBits = 0x8000000000000001ull;
+  return ((uptr)obj & kPossibleTaggedBits) != 0;
+}
+
+// Returns an address which can be used to inform TSan about synchronization
+// points (MutexLock/Unlock). The TSan infrastructure expects this to be a valid
+// address in the process space. We do a small allocation here to obtain a
+// stable address (the array backing the hash map can change). The memory is
+// never free'd (leaked) and allocation and locking are slow, but this code only
+// runs for @synchronized with tagged pointers, which is very rare.
+static uptr GetOrCreateSyncAddress(uptr addr, ThreadState *thr, uptr pc) {
+  typedef AddrHashMap<uptr, 5> Map;
+  static Map Addresses;
+  Map::Handle h(&Addresses, addr);
+  if (h.created()) {
+    ThreadIgnoreBegin(thr, pc);
+    *h = (uptr) user_alloc(thr, pc, /*size=*/1);
+    ThreadIgnoreEnd(thr, pc);
+  }
+  return *h;
+}
+
+// Returns an address on which we can synchronize given an Obj-C object pointer.
+// For normal object pointers, this is just the address of the object in memory.
+// Tagged pointers are not backed by an actual memory allocation, so we need to
+// synthesize a valid address.
+static uptr SyncAddressForObjCObject(id obj, ThreadState *thr, uptr pc) {
+  if (IsTaggedObjCPointer(obj))
+    return GetOrCreateSyncAddress((uptr)obj, thr, pc);
+  return (uptr)obj;
+}
+
+TSAN_INTERCEPTOR(int, objc_sync_enter, id obj) {
+  SCOPED_TSAN_INTERCEPTOR(objc_sync_enter, obj);
+  if (!obj) return REAL(objc_sync_enter)(obj);
+  uptr addr = SyncAddressForObjCObject(obj, thr, pc);
+  MutexPreLock(thr, pc, addr, MutexFlagWriteReentrant);
+  int result = REAL(objc_sync_enter)(obj);
+  CHECK_EQ(result, OBJC_SYNC_SUCCESS);
+  MutexPostLock(thr, pc, addr, MutexFlagWriteReentrant);
+  return result;
+}
+
+TSAN_INTERCEPTOR(int, objc_sync_exit, id obj) {
+  SCOPED_TSAN_INTERCEPTOR(objc_sync_exit, obj);
+  if (!obj) return REAL(objc_sync_exit)(obj);
+  uptr addr = SyncAddressForObjCObject(obj, thr, pc);
+  MutexUnlock(thr, pc, addr);
+  int result = REAL(objc_sync_exit)(obj);
+  if (result != OBJC_SYNC_SUCCESS) MutexInvalidAccess(thr, pc, addr);
+  return result;
+}
+
+TSAN_INTERCEPTOR(int, swapcontext, ucontext_t *oucp, const ucontext_t *ucp) {
+  {
+    SCOPED_INTERCEPTOR_RAW(swapcontext, oucp, ucp);
+  }
+  // Bacause of swapcontext() semantics we have no option but to copy its
+  // impementation here
+  if (!oucp || !ucp) {
+    errno = EINVAL;
+    return -1;
+  }
+  ThreadState *thr = cur_thread();
+  const int UCF_SWAPPED = 0x80000000;
+  oucp->uc_onstack &= ~UCF_SWAPPED;
+  thr->ignore_interceptors++;
+  int ret = getcontext(oucp);
+  if (!(oucp->uc_onstack & UCF_SWAPPED)) {
+    thr->ignore_interceptors--;
+    if (!ret) {
+      oucp->uc_onstack |= UCF_SWAPPED;
+      ret = setcontext(ucp);
+    }
+  }
+  return ret;
+}
+
+// On macOS, libc++ is always linked dynamically, so intercepting works the
+// usual way.
+#define STDCXX_INTERCEPTOR TSAN_INTERCEPTOR
+
+namespace {
+struct fake_shared_weak_count {
+  volatile a64 shared_owners;
+  volatile a64 shared_weak_owners;
+  virtual void _unused_0x0() = 0;
+  virtual void _unused_0x8() = 0;
+  virtual void on_zero_shared() = 0;
+  virtual void _unused_0x18() = 0;
+  virtual void on_zero_shared_weak() = 0;
+};
+}  // namespace
+
+// The following code adds libc++ interceptors for:
+//     void __shared_weak_count::__release_shared() _NOEXCEPT;
+//     bool __shared_count::__release_shared() _NOEXCEPT;
+// Shared and weak pointers in C++ maintain reference counts via atomics in
+// libc++.dylib, which are TSan-invisible, and this leads to false positives in
+// destructor code. These interceptors re-implements the whole functions so that
+// the mo_acq_rel semantics of the atomic decrement are visible.
+//
+// Unfortunately, the interceptors cannot simply Acquire/Release some sync
+// object and call the original function, because it would have a race between
+// the sync and the destruction of the object.  Calling both under a lock will
+// not work because the destructor can invoke this interceptor again (and even
+// in a different thread, so recursive locks don't help).
+
+STDCXX_INTERCEPTOR(void, _ZNSt3__119__shared_weak_count16__release_sharedEv,
+                   fake_shared_weak_count *o) {
+  if (!flags()->shared_ptr_interceptor)
+    return REAL(_ZNSt3__119__shared_weak_count16__release_sharedEv)(o);
+
+  SCOPED_TSAN_INTERCEPTOR(_ZNSt3__119__shared_weak_count16__release_sharedEv,
+                          o);
+  if (__tsan_atomic64_fetch_add(&o->shared_owners, -1, mo_release) == 0) {
+    Acquire(thr, pc, (uptr)&o->shared_owners);
+    o->on_zero_shared();
+    if (__tsan_atomic64_fetch_add(&o->shared_weak_owners, -1, mo_release) ==
+        0) {
+      Acquire(thr, pc, (uptr)&o->shared_weak_owners);
+      o->on_zero_shared_weak();
+    }
+  }
+}
+
+STDCXX_INTERCEPTOR(bool, _ZNSt3__114__shared_count16__release_sharedEv,
+                   fake_shared_weak_count *o) {
+  if (!flags()->shared_ptr_interceptor)
+    return REAL(_ZNSt3__114__shared_count16__release_sharedEv)(o);
+
+  SCOPED_TSAN_INTERCEPTOR(_ZNSt3__114__shared_count16__release_sharedEv, o);
+  if (__tsan_atomic64_fetch_add(&o->shared_owners, -1, mo_release) == 0) {
+    Acquire(thr, pc, (uptr)&o->shared_owners);
+    o->on_zero_shared();
+    return true;
+  }
+  return false;
+}
+
+namespace {
+struct call_once_callback_args {
+  void (*orig_func)(void *arg);
+  void *orig_arg;
+  void *flag;
+};
+
+void call_once_callback_wrapper(void *arg) {
+  call_once_callback_args *new_args = (call_once_callback_args *)arg;
+  new_args->orig_func(new_args->orig_arg);
+  __tsan_release(new_args->flag);
+}
+}  // namespace
+
+// This adds a libc++ interceptor for:
+//     void __call_once(volatile unsigned long&, void*, void(*)(void*));
+// C++11 call_once is implemented via an internal function __call_once which is
+// inside libc++.dylib, and the atomic release store inside it is thus
+// TSan-invisible. To avoid false positives, this interceptor wraps the callback
+// function and performs an explicit Release after the user code has run.
+STDCXX_INTERCEPTOR(void, _ZNSt3__111__call_onceERVmPvPFvS2_E, void *flag,
+                   void *arg, void (*func)(void *arg)) {
+  call_once_callback_args new_args = {func, arg, flag};
+  REAL(_ZNSt3__111__call_onceERVmPvPFvS2_E)(flag, &new_args,
+                                            call_once_callback_wrapper);
+}
+
+}  // namespace __tsan
+
+#endif  // SANITIZER_MAC
diff --git a/lib/tsan/tsan_interceptors_mach_vm.cpp b/lib/tsan/tsan_interceptors_mach_vm.cpp
new file mode 100644
index 0000000000..cd318f8af9
--- /dev/null
+++ b/lib/tsan/tsan_interceptors_mach_vm.cpp
@@ -0,0 +1,52 @@
+//===-- tsan_interceptors_mach_vm.cpp -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of ThreadSanitizer (TSan), a race detector.
+//
+// Interceptors for mach_vm_* user space memory routines on Darwin.
+//===----------------------------------------------------------------------===//
+
+#include "interception/interception.h"
+#include "tsan_interceptors.h"
+#include "tsan_platform.h"
+
+#include <mach/mach.h>
+
+namespace __tsan {
+
+static bool intersects_with_shadow(mach_vm_address_t *address,
+                                   mach_vm_size_t size, int flags) {
+  // VM_FLAGS_FIXED is 0x0, so we have to test for VM_FLAGS_ANYWHERE.
+  if (flags & VM_FLAGS_ANYWHERE) return false;
+  uptr ptr = *address;
+  return !IsAppMem(ptr) || !IsAppMem(ptr + size - 1);
+}
+
+TSAN_INTERCEPTOR(kern_return_t, mach_vm_allocate, vm_map_t target,
+                 mach_vm_address_t *address, mach_vm_size_t size, int flags) {
+  SCOPED_TSAN_INTERCEPTOR(mach_vm_allocate, target, address, size, flags);
+  if (target != mach_task_self())
+    return REAL(mach_vm_allocate)(target, address, size, flags);
+  if (intersects_with_shadow(address, size, flags))
+    return KERN_NO_SPACE;
+  kern_return_t res = REAL(mach_vm_allocate)(target, address, size, flags);
+  if (res == KERN_SUCCESS)
+    MemoryRangeImitateWriteOrResetRange(thr, pc, *address, size);
+  return res;
+}
+
+TSAN_INTERCEPTOR(kern_return_t, mach_vm_deallocate, vm_map_t target,
+                 mach_vm_address_t address, mach_vm_size_t size) {
+  SCOPED_TSAN_INTERCEPTOR(mach_vm_deallocate, target, address, size);
+  if (target != mach_task_self())
+    return REAL(mach_vm_deallocate)(target, address, size);
+  UnmapShadow(thr, address, size);
+  return REAL(mach_vm_deallocate)(target, address, size);
+}
+
+}  // namespace __tsan
diff --git a/lib/tsan/tsan_platform_linux.cpp b/lib/tsan/tsan_platform_linux.cpp
new file mode 100644
index 0000000000..645152a06c
--- /dev/null
+++ b/lib/tsan/tsan_platform_linux.cpp
@@ -0,0 +1,517 @@
+//===-- tsan_platform_linux.cpp -------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of ThreadSanitizer (TSan), a race detector.
+//
+// Linux- and BSD-specific code.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_platform.h"
+#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
+    SANITIZER_OPENBSD
+
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_libc.h"
+#include "sanitizer_common/sanitizer_linux.h"
+#include "sanitizer_common/sanitizer_platform_limits_netbsd.h"
+#include "sanitizer_common/sanitizer_platform_limits_openbsd.h"
+#include "sanitizer_common/sanitizer_platform_limits_posix.h"
+#include "sanitizer_common/sanitizer_posix.h"
+#include "sanitizer_common/sanitizer_procmaps.h"
+#include "sanitizer_common/sanitizer_stackdepot.h"
+#include "sanitizer_common/sanitizer_stoptheworld.h"
+#include "tsan_flags.h"
+#include "tsan_platform.h"
+#include "tsan_rtl.h"
+
+#include <fcntl.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <sys/mman.h>
+#if SANITIZER_LINUX
+#include <sys/personality.h>
+#include <setjmp.h>
+#endif
+#include <sys/syscall.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/resource.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <sched.h>
+#include <dlfcn.h>
+#if SANITIZER_LINUX
+#define __need_res_state
+#include <resolv.h>
+#endif
+
+#ifdef sa_handler
+# undef sa_handler
+#endif
+
+#ifdef sa_sigaction
+# undef sa_sigaction
+#endif
+
+#if SANITIZER_FREEBSD
+extern "C" void *__libc_stack_end;
+void *__libc_stack_end = 0;
+#endif
+
+#if SANITIZER_LINUX && defined(__aarch64__) && !SANITIZER_GO
+# define INIT_LONGJMP_XOR_KEY 1
+#else
+# define INIT_LONGJMP_XOR_KEY 0
+#endif
+
+#if INIT_LONGJMP_XOR_KEY
+#include "interception/interception.h"
+// Must be declared outside of other namespaces.
+DECLARE_REAL(int, _setjmp, void *env)
+#endif
+
+namespace __tsan {
+
+#if INIT_LONGJMP_XOR_KEY
+static void InitializeLongjmpXorKey();
+static uptr longjmp_xor_key;
+#endif
+
+#ifdef TSAN_RUNTIME_VMA
+// Runtime detected VMA size.
+uptr vmaSize;
+#endif
+
+enum {
+  MemTotal  = 0,
+  MemShadow = 1,
+  MemMeta   = 2,
+  MemFile   = 3,
+  MemMmap   = 4,
+  MemTrace  = 5,
+  MemHeap   = 6,
+  MemOther  = 7,
+  MemCount  = 8,
+};
+
+void FillProfileCallback(uptr p, uptr rss, bool file,
+                         uptr *mem, uptr stats_size) {
+  mem[MemTotal] += rss;
+  if (p >= ShadowBeg() && p < ShadowEnd())
+    mem[MemShadow] += rss;
+  else if (p >= MetaShadowBeg() && p < MetaShadowEnd())
+    mem[MemMeta] += rss;
+#if !SANITIZER_GO
+  else if (p >= HeapMemBeg() && p < HeapMemEnd())
+    mem[MemHeap] += rss;
+  else if (p >= LoAppMemBeg() && p < LoAppMemEnd())
+    mem[file ? MemFile : MemMmap] += rss;
+  else if (p >= HiAppMemBeg() && p < HiAppMemEnd())
+    mem[file ? MemFile : MemMmap] += rss;
+#else
+  else if (p >= AppMemBeg() && p < AppMemEnd())
+    mem[file ? MemFile : MemMmap] += rss;
+#endif
+  else if (p >= TraceMemBeg() && p < TraceMemEnd())
+    mem[MemTrace] += rss;
+  else
+    mem[MemOther] += rss;
+}
+
+void WriteMemoryProfile(char *buf, uptr buf_size, uptr nthread, uptr nlive) {
+  uptr mem[MemCount];
+  internal_memset(mem, 0, sizeof(mem[0]) * MemCount);
+  __sanitizer::GetMemoryProfile(FillProfileCallback, mem, 7);
+  StackDepotStats *stacks = StackDepotGetStats();
+  internal_snprintf(buf, buf_size,
+      "RSS %zd MB: shadow:%zd meta:%zd file:%zd mmap:%zd"
+      " trace:%zd heap:%zd other:%zd stacks=%zd[%zd] nthr=%zd/%zd\n",
+      mem[MemTotal] >> 20, mem[MemShadow] >> 20, mem[MemMeta] >> 20,
+      mem[MemFile] >> 20, mem[MemMmap] >> 20, mem[MemTrace] >> 20,
+      mem[MemHeap] >> 20, mem[MemOther] >> 20,
+      stacks->allocated >> 20, stacks->n_uniq_ids,
+      nlive, nthread);
+}
+
+#if SANITIZER_LINUX
+void FlushShadowMemoryCallback(
+    const SuspendedThreadsList &suspended_threads_list,
+    void *argument) {
+  ReleaseMemoryPagesToOS(ShadowBeg(), ShadowEnd());
+}
+#endif
+
+void FlushShadowMemory() {
+#if SANITIZER_LINUX
+  StopTheWorld(FlushShadowMemoryCallback, 0);
+#endif
+}
+
+#if !SANITIZER_GO
+// Mark shadow for .rodata sections with the special kShadowRodata marker.
+// Accesses to .rodata can't race, so this saves time, memory and trace space.
+static void MapRodata() {
+  // First create temp file.
+  const char *tmpdir = GetEnv("TMPDIR");
+  if (tmpdir == 0)
+    tmpdir = GetEnv("TEST_TMPDIR");
+#ifdef P_tmpdir
+  if (tmpdir == 0)
+    tmpdir = P_tmpdir;
+#endif
+  if (tmpdir == 0)
+    return;
+  char name[256];
+  internal_snprintf(name, sizeof(name), "%s/tsan.rodata.%d",
+                    tmpdir, (int)internal_getpid());
+  uptr openrv = internal_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
+  if (internal_iserror(openrv))
+    return;
+  internal_unlink(name);  // Unlink it now, so that we can reuse the buffer.
+  fd_t fd = openrv;
+  // Fill the file with kShadowRodata.
+  const uptr kMarkerSize = 512 * 1024 / sizeof(u64);
+  InternalMmapVector<u64> marker(kMarkerSize);
+  // volatile to prevent insertion of memset
+  for (volatile u64 *p = marker.data(); p < marker.data() + kMarkerSize; p++)
+    *p = kShadowRodata;
+  internal_write(fd, marker.data(), marker.size() * sizeof(u64));
+  // Map the file into memory.
+  uptr page = internal_mmap(0, GetPageSizeCached(), PROT_READ | PROT_WRITE,
+                            MAP_PRIVATE | MAP_ANONYMOUS, fd, 0);
+  if (internal_iserror(page)) {
+    internal_close(fd);
+    return;
+  }
+  // Map the file into shadow of .rodata sections.
+  MemoryMappingLayout proc_maps(/*cache_enabled*/true);
+  // Reusing the buffer 'name'.
+  MemoryMappedSegment segment(name, ARRAY_SIZE(name));
+  while (proc_maps.Next(&segment)) {
+    if (segment.filename[0] != 0 && segment.filename[0] != '[' &&
+        segment.IsReadable() && segment.IsExecutable() &&
+        !segment.IsWritable() && IsAppMem(segment.start)) {
+      // Assume it's .rodata
+      char *shadow_start = (char *)MemToShadow(segment.start);
+      char *shadow_end = (char *)MemToShadow(segment.end);
+      for (char *p = shadow_start; p < shadow_end;
+           p += marker.size() * sizeof(u64)) {
+        internal_mmap(p, Min<uptr>(marker.size() * sizeof(u64), shadow_end - p),
+                      PROT_READ, MAP_PRIVATE | MAP_FIXED, fd, 0);
+      }
+    }
+  }
+  internal_close(fd);
+}
+
+void InitializeShadowMemoryPlatform() {
+  MapRodata();
+}
+
+#endif  // #if !SANITIZER_GO
+
+void InitializePlatformEarly() {
+#ifdef TSAN_RUNTIME_VMA
+  vmaSize =
+    (MostSignificantSetBitIndex(GET_CURRENT_FRAME()) + 1);
+#if defined(__aarch64__)
+# if !SANITIZER_GO
+  if (vmaSize != 39 && vmaSize != 42 && vmaSize != 48) {
+    Printf("FATAL: ThreadSanitizer: unsupported VMA range\n");
+    Printf("FATAL: Found %zd - Supported 39, 42 and 48\n", vmaSize);
+    Die();
+  }
+#else
+  if (vmaSize != 48) {
+    Printf("FATAL: ThreadSanitizer: unsupported VMA range\n");
+    Printf("FATAL: Found %zd - Supported 48\n", vmaSize);
+    Die();
+  }
+#endif
+#elif defined(__powerpc64__)
+# if !SANITIZER_GO
+  if (vmaSize != 44 && vmaSize != 46 && vmaSize != 47) {
+    Printf("FATAL: ThreadSanitizer: unsupported VMA range\n");
+    Printf("FATAL: Found %zd - Supported 44, 46, and 47\n", vmaSize);
+    Die();
+  }
+# else
+  if (vmaSize != 46 && vmaSize != 47) {
+    Printf("FATAL: ThreadSanitizer: unsupported VMA range\n");
+    Printf("FATAL: Found %zd - Supported 46, and 47\n", vmaSize);
+    Die();
+  }
+# endif
+#endif
+#endif
+}
+
+void InitializePlatform() {
+  DisableCoreDumperIfNecessary();
+
+  // Go maps shadow memory lazily and works fine with limited address space.
+  // Unlimited stack is not a problem as well, because the executable
+  // is not compiled with -pie.
+#if !SANITIZER_GO
+  {
+    bool reexec = false;
+    // TSan doesn't play well with unlimited stack size (as stack
+    // overlaps with shadow memory). If we detect unlimited stack size,
+    // we re-exec the program with limited stack size as a best effort.
+    if (StackSizeIsUnlimited()) {
+      const uptr kMaxStackSize = 32 * 1024 * 1024;
+      VReport(1, "Program is run with unlimited stack size, which wouldn't "
+                 "work with ThreadSanitizer.\n"
+                 "Re-execing with stack size limited to %zd bytes.\n",
+              kMaxStackSize);
+      SetStackSizeLimitInBytes(kMaxStackSize);
+      reexec = true;
+    }
+
+    if (!AddressSpaceIsUnlimited()) {
+      Report("WARNING: Program is run with limited virtual address space,"
+             " which wouldn't work with ThreadSanitizer.\n");
+      Report("Re-execing with unlimited virtual address space.\n");
+      SetAddressSpaceUnlimited();
+      reexec = true;
+    }
+#if SANITIZER_LINUX && defined(__aarch64__)
+    // After patch "arm64: mm: support ARCH_MMAP_RND_BITS." is introduced in
+    // linux kernel, the random gap between stack and mapped area is increased
+    // from 128M to 36G on 39-bit aarch64. As it is almost impossible to cover
+    // this big range, we should disable randomized virtual space on aarch64.
+    int old_personality = personality(0xffffffff);
+    if (old_personality != -1 && (old_personality & ADDR_NO_RANDOMIZE) == 0) {
+      VReport(1, "WARNING: Program is run with randomized virtual address "
+              "space, which wouldn't work with ThreadSanitizer.\n"
+              "Re-execing with fixed virtual address space.\n");
+      CHECK_NE(personality(old_personality | ADDR_NO_RANDOMIZE), -1);
+      reexec = true;
+    }
+    // Initialize the xor key used in {sig}{set,long}jump.
+    InitializeLongjmpXorKey();
+#endif
+    if (reexec)
+      ReExec();
+  }
+
+  CheckAndProtect();
+  InitTlsSize();
+#endif  // !SANITIZER_GO
+}
+
+#if !SANITIZER_GO
+// Extract file descriptors passed to glibc internal __res_iclose function.
+// This is required to properly "close" the fds, because we do not see internal
+// closes within glibc. The code is a pure hack.
+int ExtractResolvFDs(void *state, int *fds, int nfd) {
+#if SANITIZER_LINUX && !SANITIZER_ANDROID
+  int cnt = 0;
+  struct __res_state *statp = (struct __res_state*)state;
+  for (int i = 0; i < MAXNS && cnt < nfd; i++) {
+    if (statp->_u._ext.nsaddrs[i] && statp->_u._ext.nssocks[i] != -1)
+      fds[cnt++] = statp->_u._ext.nssocks[i];
+  }
+  return cnt;
+#else
+  return 0;
+#endif
+}
+
+// Extract file descriptors passed via UNIX domain sockets.
+// This is requried to properly handle "open" of these fds.
+// see 'man recvmsg' and 'man 3 cmsg'.
+int ExtractRecvmsgFDs(void *msgp, int *fds, int nfd) {
+  int res = 0;
+  msghdr *msg = (msghdr*)msgp;
+  struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
+  for (; cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+    if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
+      continue;
+    int n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(fds[0]);
+    for (int i = 0; i < n; i++) {
+      fds[res++] = ((int*)CMSG_DATA(cmsg))[i];
+      if (res == nfd)
+        return res;
+    }
+  }
+  return res;
+}
+
+// Reverse operation of libc stack pointer mangling
+static uptr UnmangleLongJmpSp(uptr mangled_sp) {
+#if defined(__x86_64__)
+# if SANITIZER_LINUX
+  // Reverse of:
+  //   xor  %fs:0x30, %rsi
+  //   rol  $0x11, %rsi
+  uptr sp;
+  asm("ror  $0x11,     %0 \n"
+      "xor  %%fs:0x30, %0 \n"
+      : "=r" (sp)
+      : "0" (mangled_sp));
+  return sp;
+# else
+  return mangled_sp;
+# endif
+#elif defined(__aarch64__)
+# if SANITIZER_LINUX
+  return mangled_sp ^ longjmp_xor_key;
+# else
+  return mangled_sp;
+# endif
+#elif defined(__powerpc64__)
+  // Reverse of:
+  //   ld   r4, -28696(r13)
+  //   xor  r4, r3, r4
+  uptr xor_key;
+  asm("ld  %0, -28696(%%r13)" : "=r" (xor_key));
+  return mangled_sp ^ xor_key;
+#elif defined(__mips__)
+  return mangled_sp;
+#else
+  #error "Unknown platform"
+#endif
+}
+
+#ifdef __powerpc__
+# define LONG_JMP_SP_ENV_SLOT 0
+#elif SANITIZER_FREEBSD
+# define LONG_JMP_SP_ENV_SLOT 2
+#elif SANITIZER_NETBSD
+# define LONG_JMP_SP_ENV_SLOT 6
+#elif SANITIZER_LINUX
+# ifdef __aarch64__
+#  define LONG_JMP_SP_ENV_SLOT 13
+# elif defined(__mips64)
+#  define LONG_JMP_SP_ENV_SLOT 1
+# else
+#  define LONG_JMP_SP_ENV_SLOT 6
+# endif
+#endif
+
+uptr ExtractLongJmpSp(uptr *env) {
+  uptr mangled_sp = env[LONG_JMP_SP_ENV_SLOT];
+  return UnmangleLongJmpSp(mangled_sp);
+}
+
+#if INIT_LONGJMP_XOR_KEY
+// GLIBC mangles the function pointers in jmp_buf (used in {set,long}*jmp
+// functions) by XORing them with a random key.  For AArch64 it is a global
+// variable rather than a TCB one (as for x86_64/powerpc).  We obtain the key by
+// issuing a setjmp and XORing the SP pointer values to derive the key.
+static void InitializeLongjmpXorKey() {
+  // 1. Call REAL(setjmp), which stores the mangled SP in env.
+  jmp_buf env;
+  REAL(_setjmp)(env);
+
+  // 2. Retrieve vanilla/mangled SP.
+  uptr sp;
+  asm("mov  %0, sp" : "=r" (sp));
+  uptr mangled_sp = ((uptr *)&env)[LONG_JMP_SP_ENV_SLOT];
+
+  // 3. xor SPs to obtain key.
+  longjmp_xor_key = mangled_sp ^ sp;
+}
+#endif
+
+void ImitateTlsWrite(ThreadState *thr, uptr tls_addr, uptr tls_size) {
+  // Check that the thr object is in tls;
+  const uptr thr_beg = (uptr)thr;
+  const uptr thr_end = (uptr)thr + sizeof(*thr);
+  CHECK_GE(thr_beg, tls_addr);
+  CHECK_LE(thr_beg, tls_addr + tls_size);
+  CHECK_GE(thr_end, tls_addr);
+  CHECK_LE(thr_end, tls_addr + tls_size);
+  // Since the thr object is huge, skip it.
+  MemoryRangeImitateWrite(thr, /*pc=*/2, tls_addr, thr_beg - tls_addr);
+  MemoryRangeImitateWrite(thr, /*pc=*/2, thr_end,
+                          tls_addr + tls_size - thr_end);
+}
+
+// Note: this function runs with async signals enabled,
+// so it must not touch any tsan state.
+int call_pthread_cancel_with_cleanup(int(*fn)(void *c, void *m,
+    void *abstime), void *c, void *m, void *abstime,
+    void(*cleanup)(void *arg), void *arg) {
+  // pthread_cleanup_push/pop are hardcore macros mess.
+  // We can't intercept nor call them w/o including pthread.h.
+  int res;
+  pthread_cleanup_push(cleanup, arg);
+  res = fn(c, m, abstime);
+  pthread_cleanup_pop(0);
+  return res;
+}
+#endif  // !SANITIZER_GO
+
+#if !SANITIZER_GO
+void ReplaceSystemMalloc() { }
+#endif
+
+#if !SANITIZER_GO
+#if SANITIZER_ANDROID
+// On Android, one thread can call intercepted functions after
+// DestroyThreadState(), so add a fake thread state for "dead" threads.
+static ThreadState *dead_thread_state = nullptr;
+
+ThreadState *cur_thread() {
+  ThreadState* thr = reinterpret_cast<ThreadState*>(*get_android_tls_ptr());
+  if (thr == nullptr) {
+    __sanitizer_sigset_t emptyset;
+    internal_sigfillset(&emptyset);
+    __sanitizer_sigset_t oldset;
+    CHECK_EQ(0, internal_sigprocmask(SIG_SETMASK, &emptyset, &oldset));
+    thr = reinterpret_cast<ThreadState*>(*get_android_tls_ptr());
+    if (thr == nullptr) {
+      thr = reinterpret_cast<ThreadState*>(MmapOrDie(sizeof(ThreadState),
+                                                     "ThreadState"));
+      *get_android_tls_ptr() = reinterpret_cast<uptr>(thr);
+      if (dead_thread_state == nullptr) {
+        dead_thread_state = reinterpret_cast<ThreadState*>(
+            MmapOrDie(sizeof(ThreadState), "ThreadState"));
+        dead_thread_state->fast_state.SetIgnoreBit();
+        dead_thread_state->ignore_interceptors = 1;
+        dead_thread_state->is_dead = true;
+        *const_cast<int*>(&dead_thread_state->tid) = -1;
+        CHECK_EQ(0, internal_mprotect(dead_thread_state, sizeof(ThreadState),
+                                      PROT_READ));
+      }
+    }
+    CHECK_EQ(0, internal_sigprocmask(SIG_SETMASK, &oldset, nullptr));
+  }
+  return thr;
+}
+
+void set_cur_thread(ThreadState *thr) {
+  *get_android_tls_ptr() = reinterpret_cast<uptr>(thr);
+}
+
+void cur_thread_finalize() {
+  __sanitizer_sigset_t emptyset;
+  internal_sigfillset(&emptyset);
+  __sanitizer_sigset_t oldset;
+  CHECK_EQ(0, internal_sigprocmask(SIG_SETMASK, &emptyset, &oldset));
+  ThreadState* thr = reinterpret_cast<ThreadState*>(*get_android_tls_ptr());
+  if (thr != dead_thread_state) {
+    *get_android_tls_ptr() = reinterpret_cast<uptr>(dead_thread_state);
+    UnmapOrDie(thr, sizeof(ThreadState));
+  }
+  CHECK_EQ(0, internal_sigprocmask(SIG_SETMASK, &oldset, nullptr));
+}
+#endif  // SANITIZER_ANDROID
+#endif  // if !SANITIZER_GO
+
+}  // namespace __tsan
+
+#endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
+        // SANITIZER_OPENBSD
diff --git a/lib/tsan/tsan_platform_mac.cpp b/lib/tsan/tsan_platform_mac.cpp
new file mode 100644
index 0000000000..eea52a34e9
--- /dev/null
+++ b/lib/tsan/tsan_platform_mac.cpp
@@ -0,0 +1,324 @@
+//===-- tsan_platform_mac.cpp ---------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of ThreadSanitizer (TSan), a race detector.
+//
+// Mac-specific code.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_platform.h"
+#if SANITIZER_MAC
+
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_libc.h"
+#include "sanitizer_common/sanitizer_posix.h"
+#include "sanitizer_common/sanitizer_procmaps.h"
+#include "sanitizer_common/sanitizer_ptrauth.h"
+#include "sanitizer_common/sanitizer_stackdepot.h"
+#include "tsan_platform.h"
+#include "tsan_rtl.h"
+#include "tsan_flags.h"
+
+#include <mach/mach.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/resource.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sched.h>
+
+namespace __tsan {
+
+#if !SANITIZER_GO
+static void *SignalSafeGetOrAllocate(uptr *dst, uptr size) {
+  atomic_uintptr_t *a = (atomic_uintptr_t *)dst;
+  void *val = (void *)atomic_load_relaxed(a);
+  atomic_signal_fence(memory_order_acquire);  // Turns the previous load into
+                                              // acquire wrt signals.
+  if (UNLIKELY(val == nullptr)) {
+    val = (void *)internal_mmap(nullptr, size, PROT_READ | PROT_WRITE,
+                                MAP_PRIVATE | MAP_ANON, -1, 0);
+    CHECK(val);
+    void *cmp = nullptr;
+    if (!atomic_compare_exchange_strong(a, (uintptr_t *)&cmp, (uintptr_t)val,
+                                        memory_order_acq_rel)) {
+      internal_munmap(val, size);
+      val = cmp;
+    }
+  }
+  return val;
+}
+
+// On OS X, accessing TLVs via __thread or manually by using pthread_key_* is
+// problematic, because there are several places where interceptors are called
+// when TLVs are not accessible (early process startup, thread cleanup, ...).
+// The following provides a "poor man's TLV" implementation, where we use the
+// shadow memory of the pointer returned by pthread_self() to store a pointer to
+// the ThreadState object. The main thread's ThreadState is stored separately
+// in a static variable, because we need to access it even before the
+// shadow memory is set up.
+static uptr main_thread_identity = 0;
+ALIGNED(64) static char main_thread_state[sizeof(ThreadState)];
+static ThreadState *main_thread_state_loc = (ThreadState *)main_thread_state;
+
+// We cannot use pthread_self() before libpthread has been initialized.  Our
+// current heuristic for guarding this is checking `main_thread_identity` which
+// is only assigned in `__tsan::InitializePlatform`.
+static ThreadState **cur_thread_location() {
+  if (main_thread_identity == 0)
+    return &main_thread_state_loc;
+  uptr thread_identity = (uptr)pthread_self();
+  if (thread_identity == main_thread_identity)
+    return &main_thread_state_loc;
+  return (ThreadState **)MemToShadow(thread_identity);
+}
+
+ThreadState *cur_thread() {
+  return (ThreadState *)SignalSafeGetOrAllocate(
+      (uptr *)cur_thread_location(), sizeof(ThreadState));
+}
+
+void set_cur_thread(ThreadState *thr) {
+  *cur_thread_location() = thr;
+}
+
+// TODO(kuba.brecka): This is not async-signal-safe. In particular, we call
+// munmap first and then clear `fake_tls`; if we receive a signal in between,
+// handler will try to access the unmapped ThreadState.
+void cur_thread_finalize() {
+  ThreadState **thr_state_loc = cur_thread_location();
+  if (thr_state_loc == &main_thread_state_loc) {
+    // Calling dispatch_main() or xpc_main() actually invokes pthread_exit to
+    // exit the main thread. Let's keep the main thread's ThreadState.
+    return;
+  }
+  internal_munmap(*thr_state_loc, sizeof(ThreadState));
+  *thr_state_loc = nullptr;
+}
+#endif
+
+void FlushShadowMemory() {
+}
+
+static void RegionMemUsage(uptr start, uptr end, uptr *res, uptr *dirty) {
+  vm_address_t address = start;
+  vm_address_t end_address = end;
+  uptr resident_pages = 0;
+  uptr dirty_pages = 0;
+  while (address < end_address) {
+    vm_size_t vm_region_size;
+    mach_msg_type_number_t count = VM_REGION_EXTENDED_INFO_COUNT;
+    vm_region_extended_info_data_t vm_region_info;
+    mach_port_t object_name;
+    kern_return_t ret = vm_region_64(
+        mach_task_self(), &address, &vm_region_size, VM_REGION_EXTENDED_INFO,
+        (vm_region_info_t)&vm_region_info, &count, &object_name);
+    if (ret != KERN_SUCCESS) break;
+
+    resident_pages += vm_region_info.pages_resident;
+    dirty_pages += vm_region_info.pages_dirtied;
+
+    address += vm_region_size;
+  }
+  *res = resident_pages * GetPageSizeCached();
+  *dirty = dirty_pages * GetPageSizeCached();
+}
+
+void WriteMemoryProfile(char *buf, uptr buf_size, uptr nthread, uptr nlive) {
+  uptr shadow_res, shadow_dirty;
+  uptr meta_res, meta_dirty;
+  uptr trace_res, trace_dirty;
+  RegionMemUsage(ShadowBeg(), ShadowEnd(), &shadow_res, &shadow_dirty);
+  RegionMemUsage(MetaShadowBeg(), MetaShadowEnd(), &meta_res, &meta_dirty);
+  RegionMemUsage(TraceMemBeg(), TraceMemEnd(), &trace_res, &trace_dirty);
+
+#if !SANITIZER_GO
+  uptr low_res, low_dirty;
+  uptr high_res, high_dirty;
+  uptr heap_res, heap_dirty;
+  RegionMemUsage(LoAppMemBeg(), LoAppMemEnd(), &low_res, &low_dirty);
+  RegionMemUsage(HiAppMemBeg(), HiAppMemEnd(), &high_res, &high_dirty);
+  RegionMemUsage(HeapMemBeg(), HeapMemEnd(), &heap_res, &heap_dirty);
+#else  // !SANITIZER_GO
+  uptr app_res, app_dirty;
+  RegionMemUsage(AppMemBeg(), AppMemEnd(), &app_res, &app_dirty);
+#endif
+
+  StackDepotStats *stacks = StackDepotGetStats();
+  internal_snprintf(buf, buf_size,
+    "shadow   (0x%016zx-0x%016zx): resident %zd kB, dirty %zd kB\n"
+    "meta     (0x%016zx-0x%016zx): resident %zd kB, dirty %zd kB\n"
+    "traces   (0x%016zx-0x%016zx): resident %zd kB, dirty %zd kB\n"
+#if !SANITIZER_GO
+    "low app  (0x%016zx-0x%016zx): resident %zd kB, dirty %zd kB\n"
+    "high app (0x%016zx-0x%016zx): resident %zd kB, dirty %zd kB\n"
+    "heap     (0x%016zx-0x%016zx): resident %zd kB, dirty %zd kB\n"
+#else  // !SANITIZER_GO
+    "app      (0x%016zx-0x%016zx): resident %zd kB, dirty %zd kB\n"
+#endif
+    "stacks: %zd unique IDs, %zd kB allocated\n"
+    "threads: %zd total, %zd live\n"
+    "------------------------------\n",
+    ShadowBeg(), ShadowEnd(), shadow_res / 1024, shadow_dirty / 1024,
+    MetaShadowBeg(), MetaShadowEnd(), meta_res / 1024, meta_dirty / 1024,
+    TraceMemBeg(), TraceMemEnd(), trace_res / 1024, trace_dirty / 1024,
+#if !SANITIZER_GO
+    LoAppMemBeg(), LoAppMemEnd(), low_res / 1024, low_dirty / 1024,
+    HiAppMemBeg(), HiAppMemEnd(), high_res / 1024, high_dirty / 1024,
+    HeapMemBeg(), HeapMemEnd(), heap_res / 1024, heap_dirty / 1024,
+#else  // !SANITIZER_GO
+    AppMemBeg(), AppMemEnd(), app_res / 1024, app_dirty / 1024,
+#endif
+    stacks->n_uniq_ids, stacks->allocated / 1024,
+    nthread, nlive);
+}
+
+#if !SANITIZER_GO
+void InitializeShadowMemoryPlatform() { }
+
+// On OS X, GCD worker threads are created without a call to pthread_create. We
+// need to properly register these threads with ThreadCreate and ThreadStart.
+// These threads don't have a parent thread, as they are created "spuriously".
+// We're using a libpthread API that notifies us about a newly created thread.
+// The `thread == pthread_self()` check indicates this is actually a worker
+// thread. If it's just a regular thread, this hook is called on the parent
+// thread.
+typedef void (*pthread_introspection_hook_t)(unsigned int event,
+                                             pthread_t thread, void *addr,
+                                             size_t size);
+extern "C" pthread_introspection_hook_t pthread_introspection_hook_install(
+    pthread_introspection_hook_t hook);
+static const uptr PTHREAD_INTROSPECTION_THREAD_CREATE = 1;
+static const uptr PTHREAD_INTROSPECTION_THREAD_TERMINATE = 3;
+static pthread_introspection_hook_t prev_pthread_introspection_hook;
+static void my_pthread_introspection_hook(unsigned int event, pthread_t thread,
+                                          void *addr, size_t size) {
+  if (event == PTHREAD_INTROSPECTION_THREAD_CREATE) {
+    if (thread == pthread_self()) {
+      // The current thread is a newly created GCD worker thread.
+      ThreadState *thr = cur_thread();
+      Processor *proc = ProcCreate();
+      ProcWire(proc, thr);
+      ThreadState *parent_thread_state = nullptr;  // No parent.
+      int tid = ThreadCreate(parent_thread_state, 0, (uptr)thread, true);
+      CHECK_NE(tid, 0);
+      ThreadStart(thr, tid, GetTid(), ThreadType::Worker);
+    }
+  } else if (event == PTHREAD_INTROSPECTION_THREAD_TERMINATE) {
+    if (thread == pthread_self()) {
+      ThreadState *thr = cur_thread();
+      if (thr->tctx) {
+        DestroyThreadState();
+      }
+    }
+  }
+
+  if (prev_pthread_introspection_hook != nullptr)
+    prev_pthread_introspection_hook(event, thread, addr, size);
+}
+#endif
+
+void InitializePlatformEarly() {
+#if defined(__aarch64__)
+  uptr max_vm = GetMaxUserVirtualAddress() + 1;
+  if (max_vm != Mapping::kHiAppMemEnd) {
+    Printf("ThreadSanitizer: unsupported vm address limit %p, expected %p.\n",
+           max_vm, Mapping::kHiAppMemEnd);
+    Die();
+  }
+#endif
+}
+
+static uptr longjmp_xor_key = 0;
+
+void InitializePlatform() {
+  DisableCoreDumperIfNecessary();
+#if !SANITIZER_GO
+  CheckAndProtect();
+
+  CHECK_EQ(main_thread_identity, 0);
+  main_thread_identity = (uptr)pthread_self();
+
+  prev_pthread_introspection_hook =
+      pthread_introspection_hook_install(&my_pthread_introspection_hook);
+#endif
+
+  if (GetMacosAlignedVersion() >= MacosVersion(10, 14)) {
+    // Libsystem currently uses a process-global key; this might change.
+    const unsigned kTLSLongjmpXorKeySlot = 0x7;
+    longjmp_xor_key = (uptr)pthread_getspecific(kTLSLongjmpXorKeySlot);
+  }
+}
+
+#ifdef __aarch64__
+# define LONG_JMP_SP_ENV_SLOT \
+    ((GetMacosAlignedVersion() >= MacosVersion(10, 14)) ? 12 : 13)
+#else
+# define LONG_JMP_SP_ENV_SLOT 2
+#endif
+
+uptr ExtractLongJmpSp(uptr *env) {
+  uptr mangled_sp = env[LONG_JMP_SP_ENV_SLOT];
+  uptr sp = mangled_sp ^ longjmp_xor_key;
+  sp = (uptr)ptrauth_auth_data((void *)sp, ptrauth_key_asdb,
+                               ptrauth_string_discriminator("sp"));
+  return sp;
+}
+
+#if !SANITIZER_GO
+void ImitateTlsWrite(ThreadState *thr, uptr tls_addr, uptr tls_size) {
+  // The pointer to the ThreadState object is stored in the shadow memory
+  // of the tls.
+  uptr tls_end = tls_addr + tls_size;
+  uptr thread_identity = (uptr)pthread_self();
+  if (thread_identity == main_thread_identity) {
+    MemoryRangeImitateWrite(thr, /*pc=*/2, tls_addr, tls_size);
+  } else {
+    uptr thr_state_start = thread_identity;
+    uptr thr_state_end = thr_state_start + sizeof(uptr);
+    CHECK_GE(thr_state_start, tls_addr);
+    CHECK_LE(thr_state_start, tls_addr + tls_size);
+    CHECK_GE(thr_state_end, tls_addr);
+    CHECK_LE(thr_state_end, tls_addr + tls_size);
+    MemoryRangeImitateWrite(thr, /*pc=*/2, tls_addr,
+                            thr_state_start - tls_addr);
+    MemoryRangeImitateWrite(thr, /*pc=*/2, thr_state_end,
+                            tls_end - thr_state_end);
+  }
+}
+#endif
+
+#if !SANITIZER_GO
+// Note: this function runs with async signals enabled,
+// so it must not touch any tsan state.
+int call_pthread_cancel_with_cleanup(int(*fn)(void *c, void *m,
+    void *abstime), void *c, void *m, void *abstime,
+    void(*cleanup)(void *arg), void *arg) {
+  // pthread_cleanup_push/pop are hardcore macros mess.
+  // We can't intercept nor call them w/o including pthread.h.
+  int res;
+  pthread_cleanup_push(cleanup, arg);
+  res = fn(c, m, abstime);
+  pthread_cleanup_pop(0);
+  return res;
+}
+#endif
+
+}  // namespace __tsan
+
+#endif  // SANITIZER_MAC
diff --git a/lib/tsan/tsan_platform_posix.cpp b/lib/tsan/tsan_platform_posix.cpp
new file mode 100644
index 0000000000..1a0faee025
--- /dev/null
+++ b/lib/tsan/tsan_platform_posix.cpp
@@ -0,0 +1,167 @@
+//===-- tsan_platform_posix.cpp -------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of ThreadSanitizer (TSan), a race detector.
+//
+// POSIX-specific code.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_platform.h"
+#if SANITIZER_POSIX
+
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_errno.h"
+#include "sanitizer_common/sanitizer_libc.h"
+#include "sanitizer_common/sanitizer_procmaps.h"
+#include "tsan_platform.h"
+#include "tsan_rtl.h"
+
+namespace __tsan {
+
+static const char kShadowMemoryMappingWarning[] =
+    "FATAL: %s can not madvise shadow region [%zx, %zx] with %s (errno: %d)\n";
+static const char kShadowMemoryMappingHint[] =
+    "HINT: if %s is not supported in your environment, you may set "
+    "TSAN_OPTIONS=%s=0\n";
+
+static void NoHugePagesInShadow(uptr addr, uptr size) {
+  SetShadowRegionHugePageMode(addr, size);
+}
+
+static void DontDumpShadow(uptr addr, uptr size) {
+  if (common_flags()->use_madv_dontdump)
+    if (!DontDumpShadowMemory(addr, size)) {
+      Printf(kShadowMemoryMappingWarning, SanitizerToolName, addr, addr + size,
+             "MADV_DONTDUMP", errno);
+      Printf(kShadowMemoryMappingHint, "MADV_DONTDUMP", "use_madv_dontdump");
+      Die();
+    }
+}
+
+#if !SANITIZER_GO
+void InitializeShadowMemory() {
+  // Map memory shadow.
+  if (!MmapFixedNoReserve(ShadowBeg(), ShadowEnd() - ShadowBeg(), "shadow")) {
+    Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
+    Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
+    Die();
+  }
+  // This memory range is used for thread stacks and large user mmaps.
+  // Frequently a thread uses only a small part of stack and similarly
+  // a program uses a small part of large mmap. On some programs
+  // we see 20% memory usage reduction without huge pages for this range.
+  // FIXME: don't use constants here.
+#if defined(__x86_64__)
+  const uptr kMadviseRangeBeg  = 0x7f0000000000ull;
+  const uptr kMadviseRangeSize = 0x010000000000ull;
+#elif defined(__mips64)
+  const uptr kMadviseRangeBeg  = 0xff00000000ull;
+  const uptr kMadviseRangeSize = 0x0100000000ull;
+#elif defined(__aarch64__) && defined(__APPLE__)
+  uptr kMadviseRangeBeg = LoAppMemBeg();
+  uptr kMadviseRangeSize = LoAppMemEnd() - LoAppMemBeg();
+#elif defined(__aarch64__)
+  uptr kMadviseRangeBeg = 0;
+  uptr kMadviseRangeSize = 0;
+  if (vmaSize == 39) {
+    kMadviseRangeBeg  = 0x7d00000000ull;
+    kMadviseRangeSize = 0x0300000000ull;
+  } else if (vmaSize == 42) {
+    kMadviseRangeBeg  = 0x3f000000000ull;
+    kMadviseRangeSize = 0x01000000000ull;
+  } else {
+    DCHECK(0);
+  }
+#elif defined(__powerpc64__)
+  uptr kMadviseRangeBeg = 0;
+  uptr kMadviseRangeSize = 0;
+  if (vmaSize == 44) {
+    kMadviseRangeBeg  = 0x0f60000000ull;
+    kMadviseRangeSize = 0x0010000000ull;
+  } else if (vmaSize == 46) {
+    kMadviseRangeBeg  = 0x3f0000000000ull;
+    kMadviseRangeSize = 0x010000000000ull;
+  } else {
+    DCHECK(0);
+  }
+#endif
+  NoHugePagesInShadow(MemToShadow(kMadviseRangeBeg),
+                      kMadviseRangeSize * kShadowMultiplier);
+  DontDumpShadow(ShadowBeg(), ShadowEnd() - ShadowBeg());
+  DPrintf("memory shadow: %zx-%zx (%zuGB)\n",
+      ShadowBeg(), ShadowEnd(),
+      (ShadowEnd() - ShadowBeg()) >> 30);
+
+  // Map meta shadow.
+  const uptr meta = MetaShadowBeg();
+  const uptr meta_size = MetaShadowEnd() - meta;
+  if (!MmapFixedNoReserve(meta, meta_size, "meta shadow")) {
+    Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
+    Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
+    Die();
+  }
+  NoHugePagesInShadow(meta, meta_size);
+  DontDumpShadow(meta, meta_size);
+  DPrintf("meta shadow: %zx-%zx (%zuGB)\n",
+      meta, meta + meta_size, meta_size >> 30);
+
+  InitializeShadowMemoryPlatform();
+}
+
+static void ProtectRange(uptr beg, uptr end) {
+  CHECK_LE(beg, end);
+  if (beg == end)
+    return;
+  if (beg != (uptr)MmapFixedNoAccess(beg, end - beg)) {
+    Printf("FATAL: ThreadSanitizer can not protect [%zx,%zx]\n", beg, end);
+    Printf("FATAL: Make sure you are not using unlimited stack\n");
+    Die();
+  }
+}
+
+void CheckAndProtect() {
+  // Ensure that the binary is indeed compiled with -pie.
+  MemoryMappingLayout proc_maps(true);
+  MemoryMappedSegment segment;
+  while (proc_maps.Next(&segment)) {
+    if (IsAppMem(segment.start)) continue;
+    if (segment.start >= HeapMemEnd() && segment.start < HeapEnd()) continue;
+    if (segment.protection == 0)  // Zero page or mprotected.
+      continue;
+    if (segment.start >= VdsoBeg())  // vdso
+      break;
+    Printf("FATAL: ThreadSanitizer: unexpected memory mapping %p-%p\n",
+           segment.start, segment.end);
+    Die();
+  }
+
+#if defined(__aarch64__) && defined(__APPLE__)
+  ProtectRange(HeapMemEnd(), ShadowBeg());
+  ProtectRange(ShadowEnd(), MetaShadowBeg());
+  ProtectRange(MetaShadowEnd(), TraceMemBeg());
+#else
+  ProtectRange(LoAppMemEnd(), ShadowBeg());
+  ProtectRange(ShadowEnd(), MetaShadowBeg());
+#ifdef TSAN_MID_APP_RANGE
+  ProtectRange(MetaShadowEnd(), MidAppMemBeg());
+  ProtectRange(MidAppMemEnd(), TraceMemBeg());
+#else
+  ProtectRange(MetaShadowEnd(), TraceMemBeg());
+#endif
+  // Memory for traces is mapped lazily in MapThreadTrace.
+  // Protect the whole range for now, so that user does not map something here.
+  ProtectRange(TraceMemBeg(), TraceMemEnd());
+  ProtectRange(TraceMemEnd(), HeapMemBeg());
+  ProtectRange(HeapEnd(), HiAppMemBeg());
+#endif
+}
+#endif
+
+}  // namespace __tsan
+
+#endif  // SANITIZER_POSIX
diff --git a/lib/tsan/tsan_rtl_aarch64.S b/lib/tsan/tsan_rtl_aarch64.S
new file mode 100644
index 0000000000..e0b4c71dfe
--- /dev/null
+++ b/lib/tsan/tsan_rtl_aarch64.S
@@ -0,0 +1,245 @@
+// The content of this file is AArch64-only:
+#if defined(__aarch64__)
+
+#include "sanitizer_common/sanitizer_asm.h"
+
+#if defined(__APPLE__)
+.align  2
+
+.section  __DATA,__nl_symbol_ptr,non_lazy_symbol_pointers
+.long _setjmp$non_lazy_ptr
+_setjmp$non_lazy_ptr:
+.indirect_symbol _setjmp
+.long 0
+
+.section  __DATA,__nl_symbol_ptr,non_lazy_symbol_pointers
+.long __setjmp$non_lazy_ptr
+__setjmp$non_lazy_ptr:
+.indirect_symbol __setjmp
+.long 0
+
+.section  __DATA,__nl_symbol_ptr,non_lazy_symbol_pointers
+.long _sigsetjmp$non_lazy_ptr
+_sigsetjmp$non_lazy_ptr:
+.indirect_symbol _sigsetjmp
+.long 0
+#endif
+
+#if !defined(__APPLE__)
+.section .text
+#else
+.section __TEXT,__text
+.align 3
+#endif
+
+ASM_HIDDEN(__tsan_setjmp)
+.comm _ZN14__interception11real_setjmpE,8,8
+.globl ASM_SYMBOL_INTERCEPTOR(setjmp)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(setjmp))
+ASM_SYMBOL_INTERCEPTOR(setjmp):
+  CFI_STARTPROC
+
+  // Save frame/link register
+  stp     x29, x30, [sp, -32]!
+  CFI_DEF_CFA_OFFSET (32)
+  CFI_OFFSET (29, -32)
+  CFI_OFFSET (30, -24)
+
+  // Adjust the SP for previous frame
+  add     x29, sp, 0
+  CFI_DEF_CFA_REGISTER (29)
+
+  // Save env parameter
+  str     x0, [sp, 16]
+  CFI_OFFSET (0, -16)
+
+  // Obtain SP, first argument to `void __tsan_setjmp(uptr sp)`
+  add     x0, x29, 32
+
+  // call tsan interceptor
+  bl      ASM_SYMBOL(__tsan_setjmp)
+
+  // Restore env parameter
+  ldr     x0, [sp, 16]
+  CFI_RESTORE (0)
+
+  // Restore frame/link register
+  ldp     x29, x30, [sp], 32
+  CFI_RESTORE (29)
+  CFI_RESTORE (30)
+  CFI_DEF_CFA (31, 0)
+
+  // tail jump to libc setjmp
+#if !defined(__APPLE__)
+  adrp    x1, :got:_ZN14__interception11real_setjmpE
+  ldr     x1, [x1, #:got_lo12:_ZN14__interception11real_setjmpE]
+  ldr     x1, [x1]
+#else
+  adrp    x1, _setjmp$non_lazy_ptr@page
+  add     x1, x1, _setjmp$non_lazy_ptr@pageoff
+  ldr     x1, [x1]
+#endif
+  br      x1
+
+  CFI_ENDPROC
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(setjmp))
+
+.comm _ZN14__interception12real__setjmpE,8,8
+.globl ASM_SYMBOL_INTERCEPTOR(_setjmp)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(_setjmp))
+ASM_SYMBOL_INTERCEPTOR(_setjmp):
+  CFI_STARTPROC
+
+  // Save frame/link register
+  stp     x29, x30, [sp, -32]!
+  CFI_DEF_CFA_OFFSET (32)
+  CFI_OFFSET (29, -32)
+  CFI_OFFSET (30, -24)
+
+  // Adjust the SP for previous frame
+  add     x29, sp, 0
+  CFI_DEF_CFA_REGISTER (29)
+
+  // Save env parameter
+  str     x0, [sp, 16]
+  CFI_OFFSET (0, -16)
+
+  // Obtain SP, first argument to `void __tsan_setjmp(uptr sp)`
+  add     x0, x29, 32
+
+  // call tsan interceptor
+  bl      ASM_SYMBOL(__tsan_setjmp)
+
+  // Restore env parameter
+  ldr     x0, [sp, 16]
+  CFI_RESTORE (0)
+
+  // Restore frame/link register
+  ldp     x29, x30, [sp], 32
+  CFI_RESTORE (29)
+  CFI_RESTORE (30)
+  CFI_DEF_CFA (31, 0)
+
+  // tail jump to libc setjmp
+#if !defined(__APPLE__)
+  adrp    x1, :got:_ZN14__interception12real__setjmpE
+  ldr     x1, [x1, #:got_lo12:_ZN14__interception12real__setjmpE]
+  ldr     x1, [x1]
+#else
+  adrp    x1, __setjmp$non_lazy_ptr@page
+  add     x1, x1, __setjmp$non_lazy_ptr@pageoff
+  ldr     x1, [x1]
+#endif
+  br      x1
+
+  CFI_ENDPROC
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(_setjmp))
+
+.comm _ZN14__interception14real_sigsetjmpE,8,8
+.globl ASM_SYMBOL_INTERCEPTOR(sigsetjmp)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(sigsetjmp))
+ASM_SYMBOL_INTERCEPTOR(sigsetjmp):
+  CFI_STARTPROC
+
+  // Save frame/link register
+  stp     x29, x30, [sp, -32]!
+  CFI_DEF_CFA_OFFSET (32)
+  CFI_OFFSET (29, -32)
+  CFI_OFFSET (30, -24)
+
+  // Adjust the SP for previous frame
+  add     x29, sp, 0
+  CFI_DEF_CFA_REGISTER (29)
+
+  // Save env and savesigs parameter
+  stp     x0, x1, [sp, 16]
+  CFI_OFFSET (0, -16)
+  CFI_OFFSET (1, -8)
+
+  // Obtain SP, first argument to `void __tsan_setjmp(uptr sp)`
+  add     x0, x29, 32
+
+  // call tsan interceptor
+  bl      ASM_SYMBOL(__tsan_setjmp)
+
+  // Restore env and savesigs parameter
+  ldp     x0, x1, [sp, 16]
+  CFI_RESTORE (0)
+  CFI_RESTORE (1)
+
+  // Restore frame/link register
+  ldp     x29, x30, [sp], 32
+  CFI_RESTORE (29)
+  CFI_RESTORE (30)
+  CFI_DEF_CFA (31, 0)
+
+  // tail jump to libc sigsetjmp
+#if !defined(__APPLE__)
+  adrp    x2, :got:_ZN14__interception14real_sigsetjmpE
+  ldr     x2, [x2, #:got_lo12:_ZN14__interception14real_sigsetjmpE]
+  ldr     x2, [x2]
+#else
+  adrp    x2, _sigsetjmp$non_lazy_ptr@page
+  add     x2, x2, _sigsetjmp$non_lazy_ptr@pageoff
+  ldr     x2, [x2]
+#endif
+  br      x2
+  CFI_ENDPROC
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(sigsetjmp))
+
+#if !defined(__APPLE__)
+.comm _ZN14__interception16real___sigsetjmpE,8,8
+.globl ASM_SYMBOL_INTERCEPTOR(__sigsetjmp)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(__sigsetjmp))
+ASM_SYMBOL_INTERCEPTOR(__sigsetjmp):
+  CFI_STARTPROC
+
+  // Save frame/link register
+  stp     x29, x30, [sp, -32]!
+  CFI_DEF_CFA_OFFSET (32)
+  CFI_OFFSET (29, -32)
+  CFI_OFFSET (30, -24)
+
+  // Adjust the SP for previous frame
+  add     x29, sp, 0
+  CFI_DEF_CFA_REGISTER (29)
+
+  // Save env and savesigs parameter
+  stp     x0, x1, [sp, 16]
+  CFI_OFFSET (0, -16)
+  CFI_OFFSET (1, -8)
+
+  // Obtain SP, first argument to `void __tsan_setjmp(uptr sp)`
+  add     x0, x29, 32
+
+  // call tsan interceptor
+  bl      ASM_SYMBOL(__tsan_setjmp)
+
+  // Restore env and savesigs parameter
+  ldp     x0, x1, [sp, 16]
+  CFI_RESTORE (0)
+  CFI_RESTORE (1)
+
+  // Restore frame/link register
+  ldp     x29, x30, [sp], 32
+  CFI_RESTORE (29)
+  CFI_RESTORE (30)
+  CFI_DEF_CFA (31, 0)
+
+  // tail jump to libc __sigsetjmp
+#if !defined(__APPLE__)
+  adrp    x2, :got:_ZN14__interception16real___sigsetjmpE
+  ldr     x2, [x2, #:got_lo12:_ZN14__interception16real___sigsetjmpE]
+  ldr     x2, [x2]
+#else
+  adrp    x2, ASM_SYMBOL(__sigsetjmp)@page
+  add     x2, x2, ASM_SYMBOL(__sigsetjmp)@pageoff
+#endif
+  br      x2
+  CFI_ENDPROC
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(__sigsetjmp))
+#endif
+
+NO_EXEC_STACK_DIRECTIVE
+
+#endif
diff --git a/lib/tsan/tsan_rtl_amd64.S b/lib/tsan/tsan_rtl_amd64.S
new file mode 100644
index 0000000000..5913aa360c
--- /dev/null
+++ b/lib/tsan/tsan_rtl_amd64.S
@@ -0,0 +1,366 @@
+// The content of this file is x86_64-only:
+#if defined(__x86_64__)
+
+#include "sanitizer_common/sanitizer_asm.h"
+
+#if !defined(__APPLE__)
+.section .text
+#else
+.section __TEXT,__text
+#endif
+
+ASM_HIDDEN(__tsan_trace_switch)
+.globl ASM_SYMBOL(__tsan_trace_switch_thunk)
+ASM_SYMBOL(__tsan_trace_switch_thunk):
+  CFI_STARTPROC
+  # Save scratch registers.
+  push %rax
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rax, 0)
+  push %rcx
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rcx, 0)
+  push %rdx
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rdx, 0)
+  push %rsi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rsi, 0)
+  push %rdi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rdi, 0)
+  push %r8
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%r8, 0)
+  push %r9
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%r9, 0)
+  push %r10
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%r10, 0)
+  push %r11
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%r11, 0)
+  # Align stack frame.
+  push %rbx  # non-scratch
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rbx, 0)
+  mov %rsp, %rbx  # save current rsp
+  CFI_DEF_CFA_REGISTER(%rbx)
+  shr $4, %rsp  # clear 4 lsb, align to 16
+  shl $4, %rsp
+
+  call ASM_SYMBOL(__tsan_trace_switch)
+
+  # Unalign stack frame back.
+  mov %rbx, %rsp  # restore the original rsp
+  CFI_DEF_CFA_REGISTER(%rsp)
+  pop %rbx
+  CFI_ADJUST_CFA_OFFSET(-8)
+  # Restore scratch registers.
+  pop %r11
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %r10
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %r9
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %r8
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rdi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rsi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rdx
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rcx
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rax
+  CFI_ADJUST_CFA_OFFSET(-8)
+  CFI_RESTORE(%rax)
+  CFI_RESTORE(%rbx)
+  CFI_RESTORE(%rcx)
+  CFI_RESTORE(%rdx)
+  CFI_RESTORE(%rsi)
+  CFI_RESTORE(%rdi)
+  CFI_RESTORE(%r8)
+  CFI_RESTORE(%r9)
+  CFI_RESTORE(%r10)
+  CFI_RESTORE(%r11)
+  ret
+  CFI_ENDPROC
+
+ASM_HIDDEN(__tsan_report_race)
+.globl ASM_SYMBOL(__tsan_report_race_thunk)
+ASM_SYMBOL(__tsan_report_race_thunk):
+  CFI_STARTPROC
+  # Save scratch registers.
+  push %rax
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rax, 0)
+  push %rcx
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rcx, 0)
+  push %rdx
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rdx, 0)
+  push %rsi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rsi, 0)
+  push %rdi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rdi, 0)
+  push %r8
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%r8, 0)
+  push %r9
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%r9, 0)
+  push %r10
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%r10, 0)
+  push %r11
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%r11, 0)
+  # Align stack frame.
+  push %rbx  # non-scratch
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rbx, 0)
+  mov %rsp, %rbx  # save current rsp
+  CFI_DEF_CFA_REGISTER(%rbx)
+  shr $4, %rsp  # clear 4 lsb, align to 16
+  shl $4, %rsp
+
+  call ASM_SYMBOL(__tsan_report_race)
+
+  # Unalign stack frame back.
+  mov %rbx, %rsp  # restore the original rsp
+  CFI_DEF_CFA_REGISTER(%rsp)
+  pop %rbx
+  CFI_ADJUST_CFA_OFFSET(-8)
+  # Restore scratch registers.
+  pop %r11
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %r10
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %r9
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %r8
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rdi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rsi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rdx
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rcx
+  CFI_ADJUST_CFA_OFFSET(-8)
+  pop %rax
+  CFI_ADJUST_CFA_OFFSET(-8)
+  CFI_RESTORE(%rax)
+  CFI_RESTORE(%rbx)
+  CFI_RESTORE(%rcx)
+  CFI_RESTORE(%rdx)
+  CFI_RESTORE(%rsi)
+  CFI_RESTORE(%rdi)
+  CFI_RESTORE(%r8)
+  CFI_RESTORE(%r9)
+  CFI_RESTORE(%r10)
+  CFI_RESTORE(%r11)
+  ret
+  CFI_ENDPROC
+
+ASM_HIDDEN(__tsan_setjmp)
+#if defined(__NetBSD__)
+.comm _ZN14__interception15real___setjmp14E,8,8
+#elif !defined(__APPLE__)
+.comm _ZN14__interception11real_setjmpE,8,8
+#endif
+#if defined(__NetBSD__)
+.globl ASM_SYMBOL_INTERCEPTOR(__setjmp14)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(__setjmp14))
+ASM_SYMBOL_INTERCEPTOR(__setjmp14):
+#else
+.globl ASM_SYMBOL_INTERCEPTOR(setjmp)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(setjmp))
+ASM_SYMBOL_INTERCEPTOR(setjmp):
+#endif
+  CFI_STARTPROC
+  // save env parameter
+  push %rdi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rdi, 0)
+  // obtain SP, store in %rdi, first argument to `void __tsan_setjmp(uptr sp)`
+#if defined(__FreeBSD__) || defined(__NetBSD__)
+  lea 8(%rsp), %rdi
+#elif defined(__linux__) || defined(__APPLE__)
+  lea 16(%rsp), %rdi
+#else
+# error "Unknown platform"
+#endif
+  // call tsan interceptor
+  call ASM_SYMBOL(__tsan_setjmp)
+  // restore env parameter
+  pop %rdi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  CFI_RESTORE(%rdi)
+  // tail jump to libc setjmp
+  movl $0, %eax
+#if defined(__NetBSD__)
+  movq _ZN14__interception15real___setjmp14E@GOTPCREL(%rip), %rdx
+  jmp *(%rdx)
+#elif !defined(__APPLE__)
+  movq _ZN14__interception11real_setjmpE@GOTPCREL(%rip), %rdx
+  jmp *(%rdx)
+#else
+  jmp ASM_SYMBOL(setjmp)
+#endif
+  CFI_ENDPROC
+#if defined(__NetBSD__)
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(__setjmp14))
+#else
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(setjmp))
+#endif
+
+.comm _ZN14__interception12real__setjmpE,8,8
+.globl ASM_SYMBOL_INTERCEPTOR(_setjmp)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(_setjmp))
+ASM_SYMBOL_INTERCEPTOR(_setjmp):
+  CFI_STARTPROC
+  // save env parameter
+  push %rdi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rdi, 0)
+  // obtain SP, store in %rdi, first argument to `void __tsan_setjmp(uptr sp)`
+#if defined(__FreeBSD__) || defined(__NetBSD__)
+  lea 8(%rsp), %rdi
+#elif defined(__linux__) || defined(__APPLE__)
+  lea 16(%rsp), %rdi
+#else
+# error "Unknown platform"
+#endif
+  // call tsan interceptor
+  call ASM_SYMBOL(__tsan_setjmp)
+  // restore env parameter
+  pop %rdi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  CFI_RESTORE(%rdi)
+  // tail jump to libc setjmp
+  movl $0, %eax
+#if !defined(__APPLE__)
+  movq _ZN14__interception12real__setjmpE@GOTPCREL(%rip), %rdx
+  jmp *(%rdx)
+#else
+  jmp ASM_SYMBOL(_setjmp)
+#endif
+  CFI_ENDPROC
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(_setjmp))
+
+#if defined(__NetBSD__)
+.comm _ZN14__interception18real___sigsetjmp14E,8,8
+.globl ASM_SYMBOL_INTERCEPTOR(__sigsetjmp14)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(__sigsetjmp14))
+ASM_SYMBOL_INTERCEPTOR(__sigsetjmp14):
+#else
+.comm _ZN14__interception14real_sigsetjmpE,8,8
+.globl ASM_SYMBOL_INTERCEPTOR(sigsetjmp)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(sigsetjmp))
+ASM_SYMBOL_INTERCEPTOR(sigsetjmp):
+#endif
+  CFI_STARTPROC
+  // save env parameter
+  push %rdi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rdi, 0)
+  // save savesigs parameter
+  push %rsi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rsi, 0)
+  // align stack frame
+  sub $8, %rsp
+  CFI_ADJUST_CFA_OFFSET(8)
+  // obtain SP, store in %rdi, first argument to `void __tsan_setjmp(uptr sp)`
+#if defined(__FreeBSD__) || defined(__NetBSD__)
+  lea 24(%rsp), %rdi
+#elif defined(__linux__) || defined(__APPLE__)
+  lea 32(%rsp), %rdi
+#else
+# error "Unknown platform"
+#endif
+  // call tsan interceptor
+  call ASM_SYMBOL(__tsan_setjmp)
+  // unalign stack frame
+  add $8, %rsp
+  CFI_ADJUST_CFA_OFFSET(-8)
+  // restore savesigs parameter
+  pop %rsi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  CFI_RESTORE(%rsi)
+  // restore env parameter
+  pop %rdi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  CFI_RESTORE(%rdi)
+  // tail jump to libc sigsetjmp
+  movl $0, %eax
+#if defined(__NetBSD__)
+  movq _ZN14__interception18real___sigsetjmp14E@GOTPCREL(%rip), %rdx
+  jmp *(%rdx)
+#elif !defined(__APPLE__)
+  movq _ZN14__interception14real_sigsetjmpE@GOTPCREL(%rip), %rdx
+  jmp *(%rdx)
+#else
+  jmp ASM_SYMBOL(sigsetjmp)
+#endif
+  CFI_ENDPROC
+#if defined(__NetBSD__)
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(__sigsetjmp14))
+#else
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(sigsetjmp))
+#endif
+
+#if !defined(__APPLE__) && !defined(__NetBSD__)
+.comm _ZN14__interception16real___sigsetjmpE,8,8
+.globl ASM_SYMBOL_INTERCEPTOR(__sigsetjmp)
+ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(__sigsetjmp))
+ASM_SYMBOL_INTERCEPTOR(__sigsetjmp):
+  CFI_STARTPROC
+  // save env parameter
+  push %rdi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rdi, 0)
+  // save savesigs parameter
+  push %rsi
+  CFI_ADJUST_CFA_OFFSET(8)
+  CFI_REL_OFFSET(%rsi, 0)
+  // align stack frame
+  sub $8, %rsp
+  CFI_ADJUST_CFA_OFFSET(8)
+  // obtain SP, store in %rdi, first argument to `void __tsan_setjmp(uptr sp)`
+#if defined(__FreeBSD__)
+  lea 24(%rsp), %rdi
+#else
+  lea 32(%rsp), %rdi
+#endif
+  // call tsan interceptor
+  call ASM_SYMBOL(__tsan_setjmp)
+  // unalign stack frame
+  add $8, %rsp
+  CFI_ADJUST_CFA_OFFSET(-8)
+  // restore savesigs parameter
+  pop %rsi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  CFI_RESTORE(%rsi)
+  // restore env parameter
+  pop %rdi
+  CFI_ADJUST_CFA_OFFSET(-8)
+  CFI_RESTORE(%rdi)
+  // tail jump to libc sigsetjmp
+  movl $0, %eax
+  movq _ZN14__interception16real___sigsetjmpE@GOTPCREL(%rip), %rdx
+  jmp *(%rdx)
+  CFI_ENDPROC
+ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(__sigsetjmp))
+#endif  // !defined(__APPLE__) && !defined(__NetBSD__)
+
+NO_EXEC_STACK_DIRECTIVE
+
+#endif
diff --git a/lib/tsan/tsan_rtl_mips64.S b/lib/tsan/tsan_rtl_mips64.S
new file mode 100644
index 0000000000..d0f7a3f9af
--- /dev/null
+++ b/lib/tsan/tsan_rtl_mips64.S
@@ -0,0 +1,214 @@
+.section .text
+.set noreorder
+
+.hidden __tsan_setjmp
+.comm _ZN14__interception11real_setjmpE,8,8
+.globl setjmp
+.type setjmp, @function
+setjmp:
+
+  // save env parameters
+  daddiu $sp,$sp,-40
+  sd $s0,32($sp)
+  sd $ra,24($sp)
+  sd $fp,16($sp)
+  sd $gp,8($sp)
+
+  // calculate and save pointer to GOT
+  lui $gp,%hi(%neg(%gp_rel(setjmp)))
+  daddu $gp,$gp,$t9
+  daddiu $gp,$gp,%lo(%neg(%gp_rel(setjmp)))
+  move $s0,$gp
+
+  // save jmp_buf
+  sd $a0,0($sp)
+
+  // obtain $sp
+  dadd $a0,$zero,$sp
+
+  // call tsan interceptor
+  jal __tsan_setjmp
+  daddiu $a1,$a0,40
+
+  // restore jmp_buf
+  ld $a0,0($sp)
+
+  // restore gp
+  move $gp,$s0
+
+  // load pointer of libc setjmp to t9
+  dla $t9,(_ZN14__interception11real_setjmpE) 
+
+  // restore env parameters
+  ld $gp,8($sp)
+  ld $fp,16($sp)
+  ld $ra,24($sp)
+  ld $s0,32($sp)
+  daddiu $sp,$sp,40
+
+  // tail jump to libc setjmp
+  ld $t9,0($t9)
+  jr $t9
+  nop
+
+.size setjmp, .-setjmp
+
+.hidden __tsan_setjmp
+.globl _setjmp
+.comm _ZN14__interception12real__setjmpE,8,8
+.type _setjmp, @function
+_setjmp:
+
+  // Save env parameters
+  daddiu $sp,$sp,-40
+  sd $s0,32($sp)
+  sd $ra,24($sp)
+  sd $fp,16($sp)
+  sd $gp,8($sp)
+
+  // calculate and save pointer to GOT
+  lui $gp,%hi(%neg(%gp_rel(_setjmp)))
+  daddu $gp,$gp,$t9
+  daddiu $gp,$gp,%lo(%neg(%gp_rel(_setjmp)))
+  move $s0,$gp
+
+  // save jmp_buf
+  sd $a0,0($sp)
+
+  // obtain $sp
+  dadd $a0,$zero,$sp
+
+  // call tsan interceptor
+  jal __tsan_setjmp
+  daddiu $a1,$a0,40
+
+  // restore jmp_buf
+  ld $a0,0($sp)
+
+  // restore gp
+  move $gp,$s0
+
+  // load pointer of libc _setjmp to t9
+  dla $t9,(_ZN14__interception12real__setjmpE)
+
+  // restore env parameters
+  ld $gp,8($sp)
+  ld $fp,16($sp)
+  ld $ra,24($sp)
+  ld $s0,32($sp)
+  daddiu $sp,$sp,40
+
+  // tail jump to libc _setjmp
+  ld $t9,0($t9)
+  jr $t9
+  nop
+
+.size _setjmp, .-_setjmp
+
+.hidden __tsan_setjmp
+.globl sigsetjmp
+.comm _ZN14__interception14real_sigsetjmpE,8,8
+.type sigsetjmp, @function
+sigsetjmp:
+
+  // Save env parameters
+  daddiu $sp,$sp,-48
+  sd $s0,40($sp)
+  sd $ra,32($sp)
+  sd $fp,24($sp)
+  sd $gp,16($sp)
+
+  // calculate and save pointer to GOT
+  lui $gp,%hi(%neg(%gp_rel(sigsetjmp)))
+  daddu $gp,$gp,$t9
+  daddiu $gp,$gp,%lo(%neg(%gp_rel(sigsetjmp)))
+  move $s0,$gp
+
+  // save jmp_buf and savesig
+  sd $a0,0($sp)
+  sd $a1,8($sp)
+
+  // obtain $sp
+  dadd $a0,$zero,$sp
+
+  // call tsan interceptor
+  jal __tsan_setjmp
+  daddiu $a1,$a0,48
+
+  // restore jmp_buf and savesig
+  ld $a0,0($sp)
+  ld $a1,8($sp)
+
+  // restore gp
+  move $gp,$s0
+
+  // load pointer of libc sigsetjmp to t9
+  dla $t9,(_ZN14__interception14real_sigsetjmpE) 
+
+  // restore env parameters
+  ld $gp,16($sp)
+  ld $fp,24($sp)
+  ld $ra,32($sp)
+  ld $s0,40($sp)
+  daddiu $sp,$sp,48
+
+  // tail jump to libc sigsetjmp
+  ld $t9,0($t9)
+  jr $t9
+  nop
+
+.size sigsetjmp, .-sigsetjmp
+
+.hidden __tsan_setjmp
+.comm _ZN14__interception16real___sigsetjmpE,8,8
+.globl __sigsetjmp
+.type __sigsetjmp, @function
+__sigsetjmp:
+
+  // Save env parameters
+  daddiu $sp,$sp,-48
+  sd $s0,40($sp)
+  sd $ra,32($sp)
+  sd $fp,24($sp)
+  sd $gp,16($sp)
+
+  // calculate and save pointer to GOT
+  lui $gp,%hi(%neg(%gp_rel(__sigsetjmp)))
+  daddu $gp,$gp,$t9
+  daddiu $gp,$gp,%lo(%neg(%gp_rel(__sigsetjmp)))
+  move $s0,$gp
+
+  // save jmp_buf and savesig
+  sd $a0,0($sp)
+  sd $a1,8($sp)
+
+  // obtain $sp
+  dadd $a0,$zero,$sp
+
+  // call tsan interceptor
+  jal __tsan_setjmp
+  daddiu $a1,$a0,48
+
+  // restore jmp_buf and savesig
+  ld $a0,0($sp)
+  ld $a1,8($sp)
+
+  // restore gp
+  move $gp,$s0
+
+  // load pointer to libc __sigsetjmp in t9
+  dla $t9,(_ZN14__interception16real___sigsetjmpE)
+
+  // restore env parameters
+  ld $gp,16($sp)
+  ld $fp,24($sp)
+  ld $ra,32($sp)
+  ld $s0,40($sp)
+  daddiu $sp,$sp,48
+
+  // tail jump to libc __sigsetjmp
+  ld $t9,0($t9)
+  jr $t9
+  nop
+
+.size __sigsetjmp, .-__sigsetjmp
diff --git a/lib/tsan/tsan_rtl_ppc64.S b/lib/tsan/tsan_rtl_ppc64.S
new file mode 100644
index 0000000000..8285e21aa1
--- /dev/null
+++ b/lib/tsan/tsan_rtl_ppc64.S
@@ -0,0 +1,288 @@
+#include "tsan_ppc_regs.h"
+
+        .section .text
+        .hidden __tsan_setjmp
+        .globl _setjmp
+        .type _setjmp, @function
+        .align 4
+#if _CALL_ELF == 2
+_setjmp:
+#else
+	.section ".opd","aw"
+	.align 3
+_setjmp:
+	.quad   .L._setjmp,.TOC.@tocbase,0
+	.previous
+#endif
+.L._setjmp:
+        mflr    r0
+        stdu    r1,-48(r1)
+        std     r2,24(r1)
+        std     r3,32(r1)
+        std     r0,40(r1)
+        // r3 is the original stack pointer.
+        addi    r3,r1,48
+        // r4 is the mangled stack pointer (see glibc)
+        ld      r4,-28696(r13)
+        xor     r4,r3,r4
+        // Materialize a TOC in case we were called from libc.
+        // For big-endian, we load the TOC from the OPD.  For little-
+        // endian, we use the .TOC. symbol to find it.
+        nop
+        bcl     20,31,0f
+0:
+        mflr    r2
+#if _CALL_ELF == 2
+        addis   r2,r2,.TOC.-0b@ha
+        addi    r2,r2,.TOC.-0b@l
+#else
+        addis   r2,r2,_setjmp-0b@ha
+        addi    r2,r2,_setjmp-0b@l
+        ld      r2,8(r2)
+#endif
+        // Call the interceptor.
+        bl      __tsan_setjmp
+        nop
+        // Restore regs needed for setjmp.
+        ld      r3,32(r1)
+        ld      r0,40(r1)
+        // Emulate the real setjmp function.  We do this because we can't
+        // perform a sibcall:  The real setjmp function trashes the TOC
+        // pointer, and with a sibcall we have no way to restore it.
+        // This way we can make sure our caller's stack pointer and
+        // link register are saved correctly in the jmpbuf.
+        ld      r6,-28696(r13)
+        addi    r5,r1,48  // original stack ptr of caller
+        xor     r5,r6,r5
+        std     r5,0(r3)  // mangled stack ptr of caller
+        ld      r5,24(r1)
+        std     r5,8(r3)  // caller's saved TOC pointer
+        xor     r0,r6,r0
+        std     r0,16(r3) // caller's mangled return address
+        mfcr    r0
+        // Nonvolatiles.
+        std     r14,24(r3)
+        stfd    f14,176(r3)
+        stw     r0,172(r3) // CR
+        std     r15,32(r3)
+        stfd    f15,184(r3)
+        std     r16,40(r3)
+        stfd    f16,192(r3)
+        std     r17,48(r3)
+        stfd    f17,200(r3)
+        std     r18,56(r3)
+        stfd    f18,208(r3)
+        std     r19,64(r3)
+        stfd    f19,216(r3)
+        std     r20,72(r3)
+        stfd    f20,224(r3)
+        std     r21,80(r3)
+        stfd    f21,232(r3)
+        std     r22,88(r3)
+        stfd    f22,240(r3)
+        std     r23,96(r3)
+        stfd    f23,248(r3)
+        std     r24,104(r3)
+        stfd    f24,256(r3)
+        std     r25,112(r3)
+        stfd    f25,264(r3)
+        std     r26,120(r3)
+        stfd    f26,272(r3)
+        std     r27,128(r3)
+        stfd    f27,280(r3)
+        std     r28,136(r3)
+        stfd    f28,288(r3)
+        std     r29,144(r3)
+        stfd    f29,296(r3)
+        std     r30,152(r3)
+        stfd    f30,304(r3)
+        std     r31,160(r3)
+        stfd    f31,312(r3)
+        addi    r5,r3,320
+        mfspr   r0,256
+        stw     r0,168(r3)  // VRSAVE
+        addi    r6,r5,16
+        stvx    v20,0,r5
+        addi    r5,r5,32
+        stvx    v21,0,r6
+        addi    r6,r6,32
+        stvx    v22,0,r5
+        addi    r5,r5,32
+        stvx    v23,0,r6
+        addi    r6,r6,32
+        stvx    v24,0,r5
+        addi    r5,r5,32
+        stvx    v25,0,r6
+        addi    r6,r6,32
+        stvx    v26,0,r5
+        addi    r5,r5,32
+        stvx    v27,0,r6
+        addi    r6,r6,32
+        stvx    v28,0,r5
+        addi    r5,r5,32
+        stvx    v29,0,r6
+        addi    r6,r6,32
+        stvx    v30,0,r5
+        stvx    v31,0,r6
+        // Clear the "mask-saved" slot.
+        li      r4,0
+        stw     r4,512(r3)
+        // Restore TOC, LR, and stack and return to caller.
+        ld      r2,24(r1)
+        ld      r0,40(r1)
+        addi    r1,r1,48
+        li      r3,0  // This is the setjmp return path
+        mtlr    r0
+        blr
+        .size _setjmp, .-.L._setjmp
+
+        .globl setjmp
+        .type setjmp, @function
+        .align 4
+setjmp:
+        b       _setjmp
+        .size setjmp, .-setjmp
+
+        // sigsetjmp is like setjmp, except that the mask in r4 needs
+        // to be saved at offset 512 of the jump buffer.
+        .globl __sigsetjmp
+        .type __sigsetjmp, @function
+        .align 4
+#if _CALL_ELF == 2
+__sigsetjmp:
+#else
+	.section ".opd","aw"
+	.align 3
+__sigsetjmp:
+	.quad   .L.__sigsetjmp,.TOC.@tocbase,0
+	.previous
+#endif
+.L.__sigsetjmp:
+        mflr    r0
+        stdu    r1,-64(r1)
+        std     r2,24(r1)
+        std     r3,32(r1)
+        std     r4,40(r1)
+        std     r0,48(r1)
+        // r3 is the original stack pointer.
+        addi    r3,r1,64
+        // r4 is the mangled stack pointer (see glibc)
+        ld      r4,-28696(r13)
+        xor     r4,r3,r4
+        // Materialize a TOC in case we were called from libc.
+        // For big-endian, we load the TOC from the OPD.  For little-
+        // endian, we use the .TOC. symbol to find it.
+        nop
+        bcl     20,31,1f
+1:
+        mflr    r2
+#if _CALL_ELF == 2
+        addis   r2,r2,.TOC.-1b@ha
+        addi    r2,r2,.TOC.-1b@l
+#else
+        addis   r2,r2,_setjmp-1b@ha
+        addi    r2,r2,_setjmp-1b@l
+        ld      r2,8(r2)
+#endif
+        // Call the interceptor.
+        bl      __tsan_setjmp
+        nop
+        // Restore regs needed for __sigsetjmp.
+        ld      r3,32(r1)
+        ld      r4,40(r1)
+        ld      r0,48(r1)
+        // Emulate the real sigsetjmp function.  We do this because we can't
+        // perform a sibcall:  The real sigsetjmp function trashes the TOC
+        // pointer, and with a sibcall we have no way to restore it.
+        // This way we can make sure our caller's stack pointer and
+        // link register are saved correctly in the jmpbuf.
+        ld      r6,-28696(r13)
+        addi    r5,r1,64  // original stack ptr of caller
+        xor     r5,r6,r5
+        std     r5,0(r3)  // mangled stack ptr of caller
+        ld      r5,24(r1)
+        std     r5,8(r3)  // caller's saved TOC pointer
+        xor     r0,r6,r0
+        std     r0,16(r3) // caller's mangled return address
+        mfcr    r0
+        // Nonvolatiles.
+        std     r14,24(r3)
+        stfd    f14,176(r3)
+        stw     r0,172(r3) // CR
+        std     r15,32(r3)
+        stfd    f15,184(r3)
+        std     r16,40(r3)
+        stfd    f16,192(r3)
+        std     r17,48(r3)
+        stfd    f17,200(r3)
+        std     r18,56(r3)
+        stfd    f18,208(r3)
+        std     r19,64(r3)
+        stfd    f19,216(r3)
+        std     r20,72(r3)
+        stfd    f20,224(r3)
+        std     r21,80(r3)
+        stfd    f21,232(r3)
+        std     r22,88(r3)
+        stfd    f22,240(r3)
+        std     r23,96(r3)
+        stfd    f23,248(r3)
+        std     r24,104(r3)
+        stfd    f24,256(r3)
+        std     r25,112(r3)
+        stfd    f25,264(r3)
+        std     r26,120(r3)
+        stfd    f26,272(r3)
+        std     r27,128(r3)
+        stfd    f27,280(r3)
+        std     r28,136(r3)
+        stfd    f28,288(r3)
+        std     r29,144(r3)
+        stfd    f29,296(r3)
+        std     r30,152(r3)
+        stfd    f30,304(r3)
+        std     r31,160(r3)
+        stfd    f31,312(r3)
+        addi    r5,r3,320
+        mfspr   r0,256
+        stw     r0,168(r3) // VRSAVE
+        addi    r6,r5,16
+        stvx    v20,0,r5
+        addi    r5,r5,32
+        stvx    v21,0,r6
+        addi    r6,r6,32
+        stvx    v22,0,r5
+        addi    r5,r5,32
+        stvx    v23,0,r6
+        addi    r6,r6,32
+        stvx    v24,0,r5
+        addi    r5,r5,32
+        stvx    v25,0,r6
+        addi    r6,r6,32
+        stvx    v26,0,r5
+        addi    r5,r5,32
+        stvx    v27,0,r6
+        addi    r6,r6,32
+        stvx    v28,0,r5
+        addi    r5,r5,32
+        stvx    v29,0,r6
+        addi    r6,r6,32
+        stvx    v30,0,r5
+        stvx    v31,0,r6
+        // Save into the "mask-saved" slot.
+        stw     r4,512(r3)
+        // Restore TOC, LR, and stack and return to caller.
+        ld      r2,24(r1)
+        ld      r0,48(r1)
+        addi    r1,r1,64
+        li      r3,0  // This is the sigsetjmp return path
+        mtlr    r0
+        blr
+        .size __sigsetjmp, .-.L.__sigsetjmp
+
+        .globl sigsetjmp
+        .type sigsetjmp, @function
+        .align 4
+sigsetjmp:
+        b       __sigsetjmp
+        .size sigsetjmp, .-sigsetjmp
diff --git a/src/Compilation.zig b/src/Compilation.zig
index ad4dd4fcca..6372dbff3a 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -429,7 +429,11 @@ pub const InitOptions = struct {
     verbose_llvm_cpu_features: bool = false,
     is_test: bool = false,
     test_evented_io: bool = false,
-    is_compiler_rt_or_libc: bool = false,
+    /// Normally when you create a `Compilation`, Zig will automatically build
+    /// and link in required dependencies, such as compiler-rt and libc. When
+    /// building such dependencies themselves, this flag must be set to avoid
+    /// infinite recursion.
+    skip_linker_dependencies: bool = false,
     parent_compilation_link_libc: bool = false,
     stack_size_override: ?u64 = null,
     image_base_override: ?u64 = null,
@@ -499,7 +503,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
         .Lib => is_dyn_lib,
         .Exe => true,
     };
-    const needs_c_symbols = !options.is_compiler_rt_or_libc and
+    const needs_c_symbols = !options.skip_linker_dependencies and
         (is_exe_or_dyn_lib or (options.target.isWasm() and options.output_mode != .Obj));
 
     const comp: *Compilation = comp: {
@@ -677,6 +681,9 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             break :pic explicit;
         } else pie or must_pic;
 
+        // TSAN is implemented in C++ so it requires linking libc++.
+        const link_libcpp = options.link_libcpp or tsan;
+
         // Make a decision on whether to use Clang for translate-c and compiling C files.
         const use_clang = if (options.use_clang) |explicit| explicit else blk: {
             if (build_options.have_llvm) {
@@ -765,7 +772,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
         cache.hash.add(options.function_sections);
         cache.hash.add(strip);
         cache.hash.add(link_libc);
-        cache.hash.add(options.link_libcpp);
+        cache.hash.add(link_libcpp);
         cache.hash.add(options.output_mode);
         cache.hash.add(options.machine_code_model);
         cache.hash.addOptionalEmitLoc(options.emit_bin);
@@ -793,7 +800,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             hash.add(single_threaded);
             hash.add(dll_export_fns);
             hash.add(options.is_test);
-            hash.add(options.is_compiler_rt_or_libc);
+            hash.add(options.skip_linker_dependencies);
             hash.add(options.parent_compilation_link_libc);
 
             const digest = hash.final();
@@ -930,7 +937,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             .use_llvm = use_llvm,
             .system_linker_hack = darwin_options.system_linker_hack,
             .link_libc = link_libc,
-            .link_libcpp = options.link_libcpp,
+            .link_libcpp = link_libcpp,
             .objects = options.link_objects,
             .frameworks = options.frameworks,
             .framework_dirs = options.framework_dirs,
@@ -970,7 +977,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             .dll_export_fns = dll_export_fns,
             .error_return_tracing = error_return_tracing,
             .llvm_cpu_features = llvm_cpu_features,
-            .is_compiler_rt_or_libc = options.is_compiler_rt_or_libc,
+            .skip_linker_dependencies = options.skip_linker_dependencies,
             .parent_compilation_link_libc = options.parent_compilation_link_libc,
             .each_lib_rpath = options.each_lib_rpath orelse options.is_native_os,
             .disable_lld_caching = options.disable_lld_caching,
@@ -1044,7 +1051,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
         comp.c_object_table.putAssumeCapacityNoClobber(c_object, {});
     }
 
-    if (comp.bin_file.options.emit != null and !comp.bin_file.options.is_compiler_rt_or_libc) {
+    if (comp.bin_file.options.emit != null and !comp.bin_file.options.skip_linker_dependencies) {
         // If we need to build glibc for the target, add work items for it.
         // We go through the work queue so that building can be done in parallel.
         if (comp.wantBuildGLibCFromSource()) {
@@ -1097,9 +1104,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
         if (comp.wantBuildLibUnwindFromSource()) {
             try comp.work_queue.writeItem(.{ .libunwind = {} });
         }
-        if (build_options.have_llvm and comp.bin_file.options.output_mode != .Obj and
-            comp.bin_file.options.link_libcpp)
-        {
+        if (build_options.have_llvm and is_exe_or_dyn_lib and comp.bin_file.options.link_libcpp) {
             try comp.work_queue.writeItem(.libcxx);
             try comp.work_queue.writeItem(.libcxxabi);
         }
@@ -2772,7 +2777,7 @@ pub fn generateBuiltinZigSource(comp: *Compilation, allocator: *Allocator) ![]u8
     // in. For example, compiler_rt will not export the __chkstk symbol if it
     // knows libc will provide it, and likewise c.zig will not export memcpy.
     const link_libc = comp.bin_file.options.link_libc or
-        (comp.bin_file.options.is_compiler_rt_or_libc and comp.bin_file.options.parent_compilation_link_libc);
+        (comp.bin_file.options.skip_linker_dependencies and comp.bin_file.options.parent_compilation_link_libc);
 
     try buffer.writer().print(
         \\pub const object_format = ObjectFormat.{};
@@ -2927,7 +2932,7 @@ fn buildOutputFromZig(
         .verbose_cimport = comp.verbose_cimport,
         .verbose_llvm_cpu_features = comp.verbose_llvm_cpu_features,
         .clang_passthrough_mode = comp.clang_passthrough_mode,
-        .is_compiler_rt_or_libc = true,
+        .skip_linker_dependencies = true,
         .parent_compilation_link_libc = comp.bin_file.options.link_libc,
     });
     defer sub_compilation.destroy();
@@ -3305,7 +3310,7 @@ pub fn build_crt_file(
         .verbose_cimport = comp.verbose_cimport,
         .verbose_llvm_cpu_features = comp.verbose_llvm_cpu_features,
         .clang_passthrough_mode = comp.clang_passthrough_mode,
-        .is_compiler_rt_or_libc = true,
+        .skip_linker_dependencies = true,
         .parent_compilation_link_libc = comp.bin_file.options.link_libc,
     });
     defer sub_compilation.destroy();
@@ -3326,7 +3331,7 @@ pub fn stage1AddLinkLib(comp: *Compilation, lib_name: []const u8) !void {
     // Avoid deadlocking on building import libs such as kernel32.lib
     // This can happen when the user uses `build-exe foo.obj -lkernel32` and then
     // when we create a sub-Compilation for zig libc, it also tries to build kernel32.lib.
-    if (comp.bin_file.options.is_compiler_rt_or_libc) return;
+    if (comp.bin_file.options.skip_linker_dependencies) return;
 
     // This happens when an `extern "foo"` function is referenced by the stage1 backend.
     // If we haven't seen this library yet and we're targeting Windows, we need to queue up
diff --git a/src/glibc.zig b/src/glibc.zig
index c228d8d2ef..2e42cef519 100644
--- a/src/glibc.zig
+++ b/src/glibc.zig
@@ -962,7 +962,7 @@ fn buildSharedLib(
         .version_script = map_file_path,
         .soname = soname,
         .c_source_files = &c_source_files,
-        .is_compiler_rt_or_libc = true,
+        .skip_linker_dependencies = true,
     });
     defer sub_compilation.destroy();
 
diff --git a/src/libcxx.zig b/src/libcxx.zig
index d81562bc7e..47bf93dee3 100644
--- a/src/libcxx.zig
+++ b/src/libcxx.zig
@@ -188,6 +188,7 @@ pub fn buildLibCXX(comp: *Compilation) !void {
         .verbose_llvm_cpu_features = comp.verbose_llvm_cpu_features,
         .clang_passthrough_mode = comp.clang_passthrough_mode,
         .link_libc = true,
+        .skip_linker_dependencies = true,
     });
     defer sub_compilation.destroy();
 
@@ -308,6 +309,7 @@ pub fn buildLibCXXABI(comp: *Compilation) !void {
         .verbose_llvm_cpu_features = comp.verbose_llvm_cpu_features,
         .clang_passthrough_mode = comp.clang_passthrough_mode,
         .link_libc = true,
+        .skip_linker_dependencies = true,
     });
     defer sub_compilation.destroy();
 
diff --git a/src/libtsan.zig b/src/libtsan.zig
index 3e2c70328b..ecf15693e1 100644
--- a/src/libtsan.zig
+++ b/src/libtsan.zig
@@ -34,7 +34,7 @@ pub fn buildTsan(comp: *Compilation) !void {
     };
 
     var c_source_files = std.ArrayList(Compilation.CSourceFile).init(arena);
-    try c_source_files.ensureCapacity(tsan_sources.len + sanitizer_common_sources.len);
+    try c_source_files.ensureCapacity(c_source_files.items.len + tsan_sources.len);
 
     const tsan_include_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{"tsan"});
     for (tsan_sources) |tsan_src| {
@@ -48,6 +48,7 @@ pub fn buildTsan(comp: *Compilation) !void {
         try cflags.append("-nostdinc++");
         try cflags.append("-fvisibility-inlines-hidden");
         try cflags.append("-std=c++14");
+        try cflags.append("-fno-rtti");
 
         c_source_files.appendAssumeCapacity(.{
             .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{ "tsan", tsan_src }),
@@ -55,6 +56,51 @@ pub fn buildTsan(comp: *Compilation) !void {
         });
     }
 
+    const platform_tsan_sources = if (target.isDarwin())
+        &darwin_tsan_sources
+    else
+        &unix_tsan_sources;
+    try c_source_files.ensureCapacity(c_source_files.items.len + platform_tsan_sources.len);
+    for (platform_tsan_sources) |tsan_src| {
+        var cflags = std.ArrayList([]const u8).init(arena);
+
+        try cflags.append("-I");
+        try cflags.append(tsan_include_path);
+
+        try cflags.append("-O3");
+        try cflags.append("-DNDEBUG");
+        try cflags.append("-nostdinc++");
+        try cflags.append("-fvisibility-inlines-hidden");
+        try cflags.append("-std=c++14");
+        try cflags.append("-fno-rtti");
+
+        c_source_files.appendAssumeCapacity(.{
+            .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{ "tsan", tsan_src }),
+            .extra_flags = cflags.items,
+        });
+    }
+    {
+        const asm_source = switch (target.cpu.arch) {
+            .aarch64 => "tsan_rtl_aarch64.S",
+            .x86_64 => "tsan_rtl_amd64.S",
+            .mips64 => "tsan_rtl_mips64.S",
+            .powerpc64 => "tsan_rtl_ppc64.S",
+            else => return error.TSANUnsupportedCPUArchitecture,
+        };
+        var cflags = std.ArrayList([]const u8).init(arena);
+
+        try cflags.append("-I");
+        try cflags.append(tsan_include_path);
+
+        try cflags.append("-DNDEBUG");
+
+        c_source_files.appendAssumeCapacity(.{
+            .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{ "tsan", asm_source }),
+            .extra_flags = cflags.items,
+        });
+    }
+
+    try c_source_files.ensureCapacity(c_source_files.items.len + sanitizer_common_sources.len);
     const sanitizer_common_include_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
         "tsan", "sanitizer_common",
     });
@@ -69,6 +115,7 @@ pub fn buildTsan(comp: *Compilation) !void {
         try cflags.append("-nostdinc++");
         try cflags.append("-fvisibility-inlines-hidden");
         try cflags.append("-std=c++14");
+        try cflags.append("-fno-rtti");
 
         c_source_files.appendAssumeCapacity(.{
             .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
@@ -78,6 +125,88 @@ pub fn buildTsan(comp: *Compilation) !void {
         });
     }
 
+    const to_c_or_not_to_c_sources = if (comp.bin_file.options.link_libc)
+        &sanitizer_libcdep_sources
+    else
+        &sanitizer_nolibc_sources;
+    try c_source_files.ensureCapacity(c_source_files.items.len + to_c_or_not_to_c_sources.len);
+    for (to_c_or_not_to_c_sources) |c_src| {
+        var cflags = std.ArrayList([]const u8).init(arena);
+
+        try cflags.append("-I");
+        try cflags.append(sanitizer_common_include_path);
+
+        try cflags.append("-O3");
+        try cflags.append("-DNDEBUG");
+        try cflags.append("-nostdinc++");
+        try cflags.append("-fvisibility-inlines-hidden");
+        try cflags.append("-std=c++14");
+        try cflags.append("-fno-rtti");
+
+        c_source_files.appendAssumeCapacity(.{
+            .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
+                "tsan", "sanitizer_common", c_src,
+            }),
+            .extra_flags = cflags.items,
+        });
+    }
+
+    try c_source_files.ensureCapacity(c_source_files.items.len + sanitizer_symbolizer_sources.len);
+    for (sanitizer_symbolizer_sources) |c_src| {
+        var cflags = std.ArrayList([]const u8).init(arena);
+
+        try cflags.append("-I");
+        try cflags.append(tsan_include_path);
+
+        try cflags.append("-O3");
+        try cflags.append("-DNDEBUG");
+        try cflags.append("-nostdinc++");
+        try cflags.append("-fvisibility-inlines-hidden");
+        try cflags.append("-std=c++14");
+        try cflags.append("-fno-rtti");
+
+        c_source_files.appendAssumeCapacity(.{
+            .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
+                "tsan", "sanitizer_common", c_src,
+            }),
+            .extra_flags = cflags.items,
+        });
+    }
+
+    const interception_include_path = try comp.zig_lib_directory.join(
+        arena,
+        &[_][]const u8{"interception"},
+    );
+
+    try c_source_files.ensureCapacity(c_source_files.items.len + interception_sources.len);
+    for (interception_sources) |c_src| {
+        var cflags = std.ArrayList([]const u8).init(arena);
+
+        try cflags.append("-I");
+        try cflags.append(interception_include_path);
+
+        try cflags.append("-I");
+        try cflags.append(tsan_include_path);
+
+        try cflags.append("-O3");
+        try cflags.append("-DNDEBUG");
+        try cflags.append("-nostdinc++");
+        try cflags.append("-fvisibility-inlines-hidden");
+        try cflags.append("-std=c++14");
+        try cflags.append("-fno-rtti");
+
+        c_source_files.appendAssumeCapacity(.{
+            .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{
+                "tsan", "interception", c_src,
+            }),
+            .extra_flags = cflags.items,
+        });
+    }
+
+    const common_flags = [_][]const u8{
+        "-DTSAN_CONTAINS_UBSAN=0",
+    };
+
     const sub_compilation = try Compilation.create(comp.gpa, .{
         .local_cache_directory = comp.global_cache_directory,
         .global_cache_directory = comp.global_cache_directory,
@@ -113,6 +242,8 @@ pub fn buildTsan(comp: *Compilation) !void {
         .verbose_llvm_cpu_features = comp.verbose_llvm_cpu_features,
         .clang_passthrough_mode = comp.clang_passthrough_mode,
         .link_libc = true,
+        .skip_linker_dependencies = true,
+        .clang_argv = &common_flags,
     });
     defer sub_compilation.destroy();
 
@@ -159,6 +290,18 @@ const tsan_sources = [_][]const u8{
     "tsan_sync.cpp",
 };
 
+const darwin_tsan_sources = [_][]const u8{
+    "tsan_interceptors_mac.cpp",
+    "tsan_interceptors_mach_vm.cpp",
+    "tsan_platform_mac.cpp",
+    "tsan_platform_posix.cpp",
+};
+
+const unix_tsan_sources = [_][]const u8{
+    "tsan_platform_linux.cpp",
+    "tsan_platform_posix.cpp",
+};
+
 const sanitizer_common_sources = [_][]const u8{
     "sanitizer_allocator.cpp",
     "sanitizer_common.cpp",
@@ -203,17 +346,42 @@ const sanitizer_common_sources = [_][]const u8{
     "sanitizer_win.cpp",
 };
 
-// TODO This is next up
-//const sanitizer_nolibc_sources = [_][]const u8{
-//    "sanitizer_common_nolibc.cpp",
-//};
-//
-//const sanitizer_libcdep_sources = [_][]const u8{
-//    "sanitizer_common_libcdep.cpp",
-//    "sanitizer_allocator_checks.cpp",
-//    "sanitizer_linux_libcdep.cpp",
-//    "sanitizer_mac_libcdep.cpp",
-//    "sanitizer_posix_libcdep.cpp",
-//    "sanitizer_stoptheworld_linux_libcdep.cpp",
-//    "sanitizer_stoptheworld_netbsd_libcdep.cpp",
-//};
+const sanitizer_nolibc_sources = [_][]const u8{
+    "sanitizer_common_nolibc.cpp",
+};
+
+const sanitizer_libcdep_sources = [_][]const u8{
+    "sanitizer_common_libcdep.cpp",
+    "sanitizer_allocator_checks.cpp",
+    "sanitizer_linux_libcdep.cpp",
+    "sanitizer_mac_libcdep.cpp",
+    "sanitizer_posix_libcdep.cpp",
+    "sanitizer_stoptheworld_linux_libcdep.cpp",
+    "sanitizer_stoptheworld_netbsd_libcdep.cpp",
+};
+
+const sanitizer_symbolizer_sources = [_][]const u8{
+    "sanitizer_allocator_report.cpp",
+    "sanitizer_stackdepot.cpp",
+    "sanitizer_stacktrace.cpp",
+    "sanitizer_stacktrace_libcdep.cpp",
+    "sanitizer_stacktrace_printer.cpp",
+    "sanitizer_stacktrace_sparc.cpp",
+    "sanitizer_symbolizer.cpp",
+    "sanitizer_symbolizer_libbacktrace.cpp",
+    "sanitizer_symbolizer_libcdep.cpp",
+    "sanitizer_symbolizer_mac.cpp",
+    "sanitizer_symbolizer_markup.cpp",
+    "sanitizer_symbolizer_posix_libcdep.cpp",
+    "sanitizer_symbolizer_report.cpp",
+    "sanitizer_symbolizer_win.cpp",
+    "sanitizer_unwind_linux_libcdep.cpp",
+    "sanitizer_unwind_win.cpp",
+};
+
+const interception_sources = [_][]const u8{
+    "interception_linux.cpp",
+    "interception_mac.cpp",
+    "interception_win.cpp",
+    "interception_type_test.cpp",
+};
diff --git a/src/libunwind.zig b/src/libunwind.zig
index a0da7ee1fb..db1056b776 100644
--- a/src/libunwind.zig
+++ b/src/libunwind.zig
@@ -122,6 +122,7 @@ pub fn buildStaticLib(comp: *Compilation) !void {
         .verbose_llvm_cpu_features = comp.verbose_llvm_cpu_features,
         .clang_passthrough_mode = comp.clang_passthrough_mode,
         .link_libc = true,
+        .skip_linker_dependencies = true,
     });
     defer sub_compilation.destroy();
 
diff --git a/src/link.zig b/src/link.zig
index edeb24dc9a..530bcd0b25 100644
--- a/src/link.zig
+++ b/src/link.zig
@@ -81,7 +81,7 @@ pub const Options = struct {
     verbose_link: bool,
     dll_export_fns: bool,
     error_return_tracing: bool,
-    is_compiler_rt_or_libc: bool,
+    skip_linker_dependencies: bool,
     parent_compilation_link_libc: bool,
     each_lib_rpath: bool,
     disable_lld_caching: bool,
diff --git a/src/link/Coff.zig b/src/link/Coff.zig
index 0ba12ca45d..bea3033f88 100644
--- a/src/link/Coff.zig
+++ b/src/link/Coff.zig
@@ -835,7 +835,7 @@ fn linkWithLLD(self: *Coff, comp: *Compilation) !void {
         man.hash.addOptional(self.base.options.image_base_override);
         man.hash.addListOfBytes(self.base.options.extra_lld_args);
         man.hash.addListOfBytes(self.base.options.lib_dirs);
-        man.hash.add(self.base.options.is_compiler_rt_or_libc);
+        man.hash.add(self.base.options.skip_linker_dependencies);
         if (self.base.options.link_libc) {
             man.hash.add(self.base.options.libc_installation != null);
             if (self.base.options.libc_installation) |libc_installation| {
@@ -1125,7 +1125,7 @@ fn linkWithLLD(self: *Coff, comp: *Compilation) !void {
         }
 
         // compiler-rt, libc and libssp
-        if (is_exe_or_dyn_lib and !self.base.options.is_compiler_rt_or_libc) {
+        if (is_exe_or_dyn_lib and !self.base.options.skip_linker_dependencies) {
             if (!self.base.options.link_libc) {
                 try argv.append(comp.libc_static_lib.?.full_object_path);
             }
diff --git a/src/link/Elf.zig b/src/link/Elf.zig
index a3b58c1509..6232a64e4a 100644
--- a/src/link/Elf.zig
+++ b/src/link/Elf.zig
@@ -1310,7 +1310,7 @@ fn linkWithLLD(self: *Elf, comp: *Compilation) !void {
         man.hash.addListOfBytes(self.base.options.lib_dirs);
         man.hash.addListOfBytes(self.base.options.rpath_list);
         man.hash.add(self.base.options.each_lib_rpath);
-        man.hash.add(self.base.options.is_compiler_rt_or_libc);
+        man.hash.add(self.base.options.skip_linker_dependencies);
         man.hash.add(self.base.options.z_nodelete);
         man.hash.add(self.base.options.z_defs);
         if (self.base.options.link_libc) {
@@ -1552,7 +1552,7 @@ fn linkWithLLD(self: *Elf, comp: *Compilation) !void {
     }
 
     // libc
-    if (is_exe_or_dyn_lib and !self.base.options.is_compiler_rt_or_libc and !self.base.options.link_libc) {
+    if (is_exe_or_dyn_lib and !self.base.options.skip_linker_dependencies and !self.base.options.link_libc) {
         try argv.append(comp.libc_static_lib.?.full_object_path);
     }
 
@@ -1574,9 +1574,7 @@ fn linkWithLLD(self: *Elf, comp: *Compilation) !void {
             const arg = if (ext == .shared_library) link_lib else try std.fmt.allocPrint(arena, "-l{}", .{link_lib});
             argv.appendAssumeCapacity(arg);
         }
-    }
 
-    if (!is_obj) {
         // libc++ dep
         if (self.base.options.link_libcpp) {
             try argv.append(comp.libcxxabi_static_lib.?.full_object_path);
diff --git a/src/link/MachO.zig b/src/link/MachO.zig
index 65dbe4e5f6..17816959a3 100644
--- a/src/link/MachO.zig
+++ b/src/link/MachO.zig
@@ -438,7 +438,7 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
         man.hash.addListOfBytes(self.base.options.framework_dirs);
         man.hash.addListOfBytes(self.base.options.frameworks);
         man.hash.addListOfBytes(self.base.options.rpath_list);
-        man.hash.add(self.base.options.is_compiler_rt_or_libc);
+        man.hash.add(self.base.options.skip_linker_dependencies);
         man.hash.add(self.base.options.z_nodelete);
         man.hash.add(self.base.options.z_defs);
         if (is_dyn_lib) {
@@ -633,7 +633,7 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
         }
 
         // compiler_rt on darwin is missing some stuff, so we still build it and rely on LinkOnce
-        if (is_exe_or_dyn_lib and !self.base.options.is_compiler_rt_or_libc) {
+        if (is_exe_or_dyn_lib and !self.base.options.skip_linker_dependencies) {
             try argv.append(comp.compiler_rt_static_lib.?.full_object_path);
         }
 
diff --git a/src/link/Wasm.zig b/src/link/Wasm.zig
index 74a6607051..374fa2230b 100644
--- a/src/link/Wasm.zig
+++ b/src/link/Wasm.zig
@@ -387,7 +387,7 @@ fn linkWithLLD(self: *Wasm, comp: *Compilation) !void {
     }
 
     if (self.base.options.output_mode != .Obj and
-        !self.base.options.is_compiler_rt_or_libc and
+        !self.base.options.skip_linker_dependencies and
         !self.base.options.link_libc)
     {
         try argv.append(comp.libc_static_lib.?.full_object_path);
diff --git a/src/musl.zig b/src/musl.zig
index 080dadd3fd..6680eabb03 100644
--- a/src/musl.zig
+++ b/src/musl.zig
@@ -225,7 +225,7 @@ pub fn buildCRTFile(comp: *Compilation, crt_file: CRTFile) !void {
                 .c_source_files = &[_]Compilation.CSourceFile{
                     .{ .src_path = try comp.zig_lib_directory.join(arena, &[_][]const u8{ "libc", "musl", "libc.s" }) },
                 },
-                .is_compiler_rt_or_libc = true,
+                .skip_linker_dependencies = true,
                 .soname = "libc.so",
             });
             defer sub_compilation.destroy();