diff --git a/ci/aarch64-linux-debug.sh b/ci/aarch64-linux-debug.sh
index 0452b7d7dd..758085c759 100644
--- a/ci/aarch64-linux-debug.sh
+++ b/ci/aarch64-linux-debug.sh
@@ -67,7 +67,7 @@ stage3-debug/bin/zig build test docs \
   --zig-lib-dir "$(pwd)/../lib"
 
 # Look for HTML errors.
-tidy --drop-empty-elements no -qe ../zig-cache/langref.html
+tidy --drop-empty-elements no -qe "$ZIG_LOCAL_CACHE_DIR/langref.html"
 
 # Produce the experimental std lib documentation.
 stage3-debug/bin/zig test ../lib/std/std.zig -femit-docs -fno-emit-bin --zig-lib-dir ../lib
diff --git a/ci/aarch64-linux-release.sh b/ci/aarch64-linux-release.sh
index ef24accda4..59b7d7f9b9 100644
--- a/ci/aarch64-linux-release.sh
+++ b/ci/aarch64-linux-release.sh
@@ -67,7 +67,7 @@ stage3-release/bin/zig build test docs \
   --zig-lib-dir "$(pwd)/../lib"
 
 # Look for HTML errors.
-tidy --drop-empty-elements no -qe ../zig-cache/langref.html
+tidy --drop-empty-elements no -qe "$ZIG_LOCAL_CACHE_DIR/langref.html"
 
 # Produce the experimental std lib documentation.
 stage3-release/bin/zig test ../lib/std/std.zig -femit-docs -fno-emit-bin --zig-lib-dir ../lib
diff --git a/ci/x86_64-linux-debug.sh b/ci/x86_64-linux-debug.sh
index 6ee2ce9b89..069dc78657 100755
--- a/ci/x86_64-linux-debug.sh
+++ b/ci/x86_64-linux-debug.sh
@@ -66,7 +66,7 @@ stage3-debug/bin/zig build test docs \
   --zig-lib-dir "$(pwd)/../lib"
 
 # Look for HTML errors.
-tidy --drop-empty-elements no -qe ../zig-cache/langref.html
+tidy --drop-empty-elements no -qe "$ZIG_LOCAL_CACHE_DIR/langref.html"
 
 # Produce the experimental std lib documentation.
 stage3-debug/bin/zig test ../lib/std/std.zig -femit-docs -fno-emit-bin --zig-lib-dir ../lib
diff --git a/ci/x86_64-linux-release.sh b/ci/x86_64-linux-release.sh
index d9c1172b04..06f9e48c66 100755
--- a/ci/x86_64-linux-release.sh
+++ b/ci/x86_64-linux-release.sh
@@ -67,7 +67,7 @@ stage3-release/bin/zig build test docs \
   --zig-lib-dir "$(pwd)/../lib"
 
 # Look for HTML errors.
-tidy --drop-empty-elements no -qe ../zig-cache/langref.html
+tidy --drop-empty-elements no -qe "$ZIG_LOCAL_CACHE_DIR/langref.html"
 
 # Produce the experimental std lib documentation.
 stage3-release/bin/zig test ../lib/std/std.zig -femit-docs -fno-emit-bin --zig-lib-dir ../lib
diff --git a/lib/std/c/linux.zig b/lib/std/c/linux.zig
index cfdf5dfc45..d72fd15a57 100644
--- a/lib/std/c/linux.zig
+++ b/lib/std/c/linux.zig
@@ -229,7 +229,7 @@ pub const EAI = enum(c_int) {
 pub extern "c" fn fallocate64(fd: fd_t, mode: c_int, offset: off_t, len: off_t) c_int;
 pub extern "c" fn fopen64(noalias filename: [*:0]const u8, noalias modes: [*:0]const u8) ?*FILE;
 pub extern "c" fn fstat64(fd: fd_t, buf: *Stat) c_int;
-pub extern "c" fn fstatat64(dirfd: fd_t, path: [*:0]const u8, stat_buf: *Stat, flags: u32) c_int;
+pub extern "c" fn fstatat64(dirfd: fd_t, noalias path: [*:0]const u8, noalias stat_buf: *Stat, flags: u32) c_int;
 pub extern "c" fn ftruncate64(fd: c_int, length: off_t) c_int;
 pub extern "c" fn getrlimit64(resource: rlimit_resource, rlim: *rlimit) c_int;
 pub extern "c" fn lseek64(fd: fd_t, offset: i64, whence: c_int) i64;
diff --git a/lib/std/fs.zig b/lib/std/fs.zig
index e253aaff9e..d2df596b3e 100644
--- a/lib/std/fs.zig
+++ b/lib/std/fs.zig
@@ -150,7 +150,6 @@ pub fn copyFileAbsolute(source_path: []const u8, dest_path: []const u8, args: Co
     return Dir.copyFile(my_cwd, source_path, my_cwd, dest_path, args);
 }
 
-/// TODO update this API to avoid a getrandom syscall for every operation.
 pub const AtomicFile = struct {
     file: File,
     // TODO either replace this with rand_buf or use []u16 on Windows
@@ -2598,14 +2597,32 @@ pub const Dir = struct {
         return file.stat();
     }
 
-    pub const StatFileError = File.OpenError || StatError;
+    pub const StatFileError = File.OpenError || File.StatError || os.FStatAtError;
 
-    // TODO: improve this to use the fstatat syscall instead of making 2 syscalls here.
-    pub fn statFile(self: Dir, sub_path: []const u8) StatFileError!File.Stat {
-        var file = try self.openFile(sub_path, .{});
-        defer file.close();
-
-        return file.stat();
+    /// Returns metadata for a file inside the directory.
+    ///
+    /// On Windows, this requires three syscalls. On other operating systems, it
+    /// only takes one.
+    ///
+    /// Symlinks are followed.
+    ///
+    /// `sub_path` may be absolute, in which case `self` is ignored.
+    pub fn statFile(self: Dir, sub_path: []const u8) StatFileError!Stat {
+        switch (builtin.os.tag) {
+            .windows => {
+                var file = try self.openFile(sub_path, .{});
+                defer file.close();
+                return file.stat();
+            },
+            .wasi => {
+                const st = try os.fstatatWasi(self.fd, sub_path, os.wasi.LOOKUP_SYMLINK_FOLLOW);
+                return Stat.fromSystem(st);
+            },
+            else => {
+                const st = try os.fstatat(self.fd, sub_path, 0);
+                return Stat.fromSystem(st);
+            },
+        }
     }
 
     const Permissions = File.Permissions;
diff --git a/lib/std/fs/file.zig b/lib/std/fs/file.zig
index a1e81c9b94..cb048adb30 100644
--- a/lib/std/fs/file.zig
+++ b/lib/std/fs/file.zig
@@ -294,14 +294,17 @@ pub const File = struct {
     }
 
     pub const Stat = struct {
-        /// A number that the system uses to point to the file metadata. This number is not guaranteed to be
-        /// unique across time, as some file systems may reuse an inode after its file has been deleted.
-        /// Some systems may change the inode of a file over time.
+        /// A number that the system uses to point to the file metadata. This
+        /// number is not guaranteed to be unique across time, as some file
+        /// systems may reuse an inode after its file has been deleted. Some
+        /// systems may change the inode of a file over time.
         ///
-        /// On Linux, the inode is a structure that stores the metadata, and the inode _number_ is what
-        /// you see here: the index number of the inode.
+        /// On Linux, the inode is a structure that stores the metadata, and
+        /// the inode _number_ is what you see here: the index number of the
+        /// inode.
         ///
-        /// The FileIndex on Windows is similar. It is a number for a file that is unique to each filesystem.
+        /// The FileIndex on Windows is similar. It is a number for a file that
+        /// is unique to each filesystem.
         inode: INode,
         size: u64,
         mode: Mode,
@@ -313,6 +316,50 @@ pub const File = struct {
         mtime: i128,
         /// Creation time in nanoseconds, relative to UTC 1970-01-01.
         ctime: i128,
+
+        pub fn fromSystem(st: os.system.Stat) Stat {
+            const atime = st.atime();
+            const mtime = st.mtime();
+            const ctime = st.ctime();
+            const kind: Kind = if (builtin.os.tag == .wasi and !builtin.link_libc) switch (st.filetype) {
+                .BLOCK_DEVICE => Kind.BlockDevice,
+                .CHARACTER_DEVICE => Kind.CharacterDevice,
+                .DIRECTORY => Kind.Directory,
+                .SYMBOLIC_LINK => Kind.SymLink,
+                .REGULAR_FILE => Kind.File,
+                .SOCKET_STREAM, .SOCKET_DGRAM => Kind.UnixDomainSocket,
+                else => Kind.Unknown,
+            } else blk: {
+                const m = st.mode & os.S.IFMT;
+                switch (m) {
+                    os.S.IFBLK => break :blk Kind.BlockDevice,
+                    os.S.IFCHR => break :blk Kind.CharacterDevice,
+                    os.S.IFDIR => break :blk Kind.Directory,
+                    os.S.IFIFO => break :blk Kind.NamedPipe,
+                    os.S.IFLNK => break :blk Kind.SymLink,
+                    os.S.IFREG => break :blk Kind.File,
+                    os.S.IFSOCK => break :blk Kind.UnixDomainSocket,
+                    else => {},
+                }
+                if (builtin.os.tag == .solaris) switch (m) {
+                    os.S.IFDOOR => break :blk Kind.Door,
+                    os.S.IFPORT => break :blk Kind.EventPort,
+                    else => {},
+                };
+
+                break :blk .Unknown;
+            };
+
+            return Stat{
+                .inode = st.ino,
+                .size = @bitCast(u64, st.size),
+                .mode = st.mode,
+                .kind = kind,
+                .atime = @as(i128, atime.tv_sec) * std.time.ns_per_s + atime.tv_nsec,
+                .mtime = @as(i128, mtime.tv_sec) * std.time.ns_per_s + mtime.tv_nsec,
+                .ctime = @as(i128, ctime.tv_sec) * std.time.ns_per_s + ctime.tv_nsec,
+            };
+        }
     };
 
     pub const StatError = os.FStatError;
@@ -342,47 +389,7 @@ pub const File = struct {
         }
 
         const st = try os.fstat(self.handle);
-        const atime = st.atime();
-        const mtime = st.mtime();
-        const ctime = st.ctime();
-        const kind: Kind = if (builtin.os.tag == .wasi and !builtin.link_libc) switch (st.filetype) {
-            .BLOCK_DEVICE => Kind.BlockDevice,
-            .CHARACTER_DEVICE => Kind.CharacterDevice,
-            .DIRECTORY => Kind.Directory,
-            .SYMBOLIC_LINK => Kind.SymLink,
-            .REGULAR_FILE => Kind.File,
-            .SOCKET_STREAM, .SOCKET_DGRAM => Kind.UnixDomainSocket,
-            else => Kind.Unknown,
-        } else blk: {
-            const m = st.mode & os.S.IFMT;
-            switch (m) {
-                os.S.IFBLK => break :blk Kind.BlockDevice,
-                os.S.IFCHR => break :blk Kind.CharacterDevice,
-                os.S.IFDIR => break :blk Kind.Directory,
-                os.S.IFIFO => break :blk Kind.NamedPipe,
-                os.S.IFLNK => break :blk Kind.SymLink,
-                os.S.IFREG => break :blk Kind.File,
-                os.S.IFSOCK => break :blk Kind.UnixDomainSocket,
-                else => {},
-            }
-            if (builtin.os.tag == .solaris) switch (m) {
-                os.S.IFDOOR => break :blk Kind.Door,
-                os.S.IFPORT => break :blk Kind.EventPort,
-                else => {},
-            };
-
-            break :blk .Unknown;
-        };
-
-        return Stat{
-            .inode = st.ino,
-            .size = @bitCast(u64, st.size),
-            .mode = st.mode,
-            .kind = kind,
-            .atime = @as(i128, atime.tv_sec) * std.time.ns_per_s + atime.tv_nsec,
-            .mtime = @as(i128, mtime.tv_sec) * std.time.ns_per_s + mtime.tv_nsec,
-            .ctime = @as(i128, ctime.tv_sec) * std.time.ns_per_s + ctime.tv_nsec,
-        };
+        return Stat.fromSystem(st);
     }
 
     pub const ChmodError = std.os.FChmodError;
diff --git a/src/Module.zig b/src/Module.zig
index 83294f3068..3347280f59 100644
--- a/src/Module.zig
+++ b/src/Module.zig
@@ -4156,7 +4156,7 @@ pub fn populateBuiltinFile(mod: *Module) !void {
     file.status = .success_zir;
 }
 
-pub fn writeBuiltinFile(file: *File, builtin_pkg: *Package) !void {
+fn writeBuiltinFile(file: *File, builtin_pkg: *Package) !void {
     var af = try builtin_pkg.root_src_directory.handle.atomicFile(builtin_pkg.root_src_path, .{});
     defer af.deinit();
     try af.file.writeAll(file.source);