diff --git a/lib/std/build.zig b/lib/std/build.zig
index 4f0956d549..6ef7286f9b 100644
--- a/lib/std/build.zig
+++ b/lib/std/build.zig
@@ -2000,7 +2000,7 @@ pub const RunStep = struct {
     }
 
     pub fn addPathDir(self: *RunStep, search_path: []const u8) void {
-        const PATH = if (std.os.windows.is_the_target) "Path" else "PATH";
+        const PATH = if (builtin.os == .windows) "Path" else "PATH";
         const env_map = self.getEnvMap();
         const prev_path = env_map.get(PATH) orelse {
             env_map.set(PATH, search_path) catch unreachable;
diff --git a/lib/std/c/darwin.zig b/lib/std/c/darwin.zig
index f2e8120a0e..ebd12a0d86 100644
--- a/lib/std/c/darwin.zig
+++ b/lib/std/c/darwin.zig
@@ -36,7 +36,7 @@ const mach_hdr = if (@sizeOf(usize) == 8) mach_header_64 else mach_header;
 /// export a weak symbol here, to be overridden by the real one.
 pub extern "c" var _mh_execute_header: mach_hdr = undefined;
 comptime {
-    if (std.os.darwin.is_the_target) {
+    if (std.Target.current.isDarwin()) {
         @export("_mh_execute_header", _mh_execute_header, .Weak);
     }
 }
diff --git a/lib/std/child_process.zig b/lib/std/child_process.zig
index d786c3f4de..5fae9447a9 100644
--- a/lib/std/child_process.zig
+++ b/lib/std/child_process.zig
@@ -17,9 +17,9 @@ const TailQueue = std.TailQueue;
 const maxInt = std.math.maxInt;
 
 pub const ChildProcess = struct {
-    pid: if (os.windows.is_the_target) void else i32,
-    handle: if (os.windows.is_the_target) windows.HANDLE else void,
-    thread_handle: if (os.windows.is_the_target) windows.HANDLE else void,
+    pid: if (builtin.os == .windows) void else i32,
+    handle: if (builtin.os == .windows) windows.HANDLE else void,
+    thread_handle: if (builtin.os == .windows) windows.HANDLE else void,
 
     allocator: *mem.Allocator,
 
@@ -39,16 +39,16 @@ pub const ChildProcess = struct {
     stderr_behavior: StdIo,
 
     /// Set to change the user id when spawning the child process.
-    uid: if (os.windows.is_the_target) void else ?u32,
+    uid: if (builtin.os == .windows) void else ?u32,
 
     /// Set to change the group id when spawning the child process.
-    gid: if (os.windows.is_the_target) void else ?u32,
+    gid: if (builtin.os == .windows) void else ?u32,
 
     /// Set to change the current working directory when spawning the child process.
     cwd: ?[]const u8,
 
-    err_pipe: if (os.windows.is_the_target) void else [2]os.fd_t,
-    llnode: if (os.windows.is_the_target) void else TailQueue(*ChildProcess).Node,
+    err_pipe: if (builtin.os == .windows) void else [2]os.fd_t,
+    llnode: if (builtin.os == .windows) void else TailQueue(*ChildProcess).Node,
 
     pub const SpawnError = error{OutOfMemory} || os.ExecveError || os.SetIdError ||
         os.ChangeCurDirError || windows.CreateProcessError;
@@ -82,8 +82,8 @@ pub const ChildProcess = struct {
             .term = null,
             .env_map = null,
             .cwd = null,
-            .uid = if (os.windows.is_the_target) {} else null,
-            .gid = if (os.windows.is_the_target) {} else null,
+            .uid = if (builtin.os == .windows) {} else null,
+            .gid = if (builtin.os == .windows) {} else null,
             .stdin = null,
             .stdout = null,
             .stderr = null,
@@ -103,7 +103,7 @@ pub const ChildProcess = struct {
 
     /// On success must call `kill` or `wait`.
     pub fn spawn(self: *ChildProcess) !void {
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             return self.spawnWindows();
         } else {
             return self.spawnPosix();
@@ -117,7 +117,7 @@ pub const ChildProcess = struct {
 
     /// Forcibly terminates child process and then cleans up all resources.
     pub fn kill(self: *ChildProcess) !Term {
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             return self.killWindows(1);
         } else {
             return self.killPosix();
@@ -147,7 +147,7 @@ pub const ChildProcess = struct {
 
     /// Blocks until child process terminates and then cleans up all resources.
     pub fn wait(self: *ChildProcess) !Term {
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             return self.waitWindows();
         } else {
             return self.waitPosix();
diff --git a/lib/std/debug.zig b/lib/std/debug.zig
index 0be778b3b6..95670dc4ea 100644
--- a/lib/std/debug.zig
+++ b/lib/std/debug.zig
@@ -133,7 +133,7 @@ pub fn dumpStackTraceFromBase(bp: usize, ip: usize) void {
 /// chopping off the irrelevant frames and shifting so that the returned addresses pointer
 /// equals the passed in addresses pointer.
 pub fn captureStackTrace(first_address: ?usize, stack_trace: *builtin.StackTrace) void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const addrs = stack_trace.instruction_addresses;
         const u32_addrs_len = @intCast(u32, addrs.len);
         const first_addr = first_address orelse {
@@ -310,7 +310,7 @@ pub const StackIterator = struct {
 };
 
 pub fn writeCurrentStackTrace(out_stream: var, debug_info: *DebugInfo, tty_color: bool, start_addr: ?usize) !void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return writeCurrentStackTraceWindows(out_stream, debug_info, tty_color, start_addr);
     }
     var it = StackIterator.init(start_addr);
@@ -342,10 +342,10 @@ pub fn writeCurrentStackTraceWindows(
 /// TODO once https://github.com/ziglang/zig/issues/3157 is fully implemented,
 /// make this `noasync fn` and remove the individual noasync calls.
 pub fn printSourceAtAddress(debug_info: *DebugInfo, out_stream: var, address: usize, tty_color: bool) !void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return noasync printSourceAtAddressWindows(debug_info, out_stream, address, tty_color);
     }
-    if (os.darwin.is_the_target) {
+    if (comptime std.Target.current.isDarwin()) {
         return noasync printSourceAtAddressMacOs(debug_info, out_stream, address, tty_color);
     }
     return noasync printSourceAtAddressPosix(debug_info, out_stream, address, tty_color);
@@ -832,10 +832,10 @@ pub const OpenSelfDebugInfoError = error{
 pub fn openSelfDebugInfo(allocator: *mem.Allocator) !DebugInfo {
     if (builtin.strip_debug_info)
         return error.MissingDebugInfo;
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return noasync openSelfDebugInfoWindows(allocator);
     }
-    if (os.darwin.is_the_target) {
+    if (comptime std.Target.current.isDarwin()) {
         return noasync openSelfDebugInfoMacOs(allocator);
     }
     return noasync openSelfDebugInfoPosix(allocator);
@@ -2364,7 +2364,7 @@ pub fn attachSegfaultHandler() void {
     if (!have_segfault_handling_support) {
         @compileError("segfault handler not supported for this target");
     }
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         windows_segfault_handle = windows.kernel32.AddVectoredExceptionHandler(0, handleSegfaultWindows);
         return;
     }
@@ -2378,7 +2378,7 @@ pub fn attachSegfaultHandler() void {
 }
 
 fn resetSegfaultHandler() void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         if (windows_segfault_handle) |handle| {
             assert(windows.kernel32.RemoveVectoredExceptionHandler(handle) != 0);
             windows_segfault_handle = null;
diff --git a/lib/std/event/channel.zig b/lib/std/event/channel.zig
index 2f211d21e2..1092f2204a 100644
--- a/lib/std/event/channel.zig
+++ b/lib/std/event/channel.zig
@@ -307,7 +307,7 @@ test "std.event.Channel" {
     // https://github.com/ziglang/zig/issues/1908
     if (builtin.single_threaded) return error.SkipZigTest;
     // https://github.com/ziglang/zig/issues/3251
-    if (std.os.freebsd.is_the_target) return error.SkipZigTest;
+    if (builtin.os == .freebsd) return error.SkipZigTest;
 
     var loop: Loop = undefined;
     // TODO make a multi threaded test
diff --git a/lib/std/event/fs.zig b/lib/std/event/fs.zig
index 81fd950e44..2f64d453af 100644
--- a/lib/std/event/fs.zig
+++ b/lib/std/event/fs.zig
@@ -909,7 +909,7 @@ fn hashString(s: []const u16) u32 {
 //            var close_op_consumed = false;
 //            defer if (!close_op_consumed) close_op.finish();
 //
-//            const flags = if (os.darwin.is_the_target) os.O_SYMLINK | os.O_EVTONLY else 0;
+//            const flags = if (comptime std.Target.current.isDarwin()) os.O_SYMLINK | os.O_EVTONLY else 0;
 //            const mode = 0;
 //            const fd = try await (async openPosix(self.channel.loop, resolved_path, flags, mode) catch unreachable);
 //            close_op.setHandle(fd);
diff --git a/lib/std/event/future.zig b/lib/std/event/future.zig
index 1e3508de41..c5376bc9f6 100644
--- a/lib/std/event/future.zig
+++ b/lib/std/event/future.zig
@@ -86,7 +86,7 @@ test "std.event.Future" {
     // https://github.com/ziglang/zig/issues/1908
     if (builtin.single_threaded) return error.SkipZigTest;
     // https://github.com/ziglang/zig/issues/3251
-    if (std.os.freebsd.is_the_target) return error.SkipZigTest;
+    if (builtin.os == .freebsd) return error.SkipZigTest;
 
     const allocator = std.heap.direct_allocator;
 
diff --git a/lib/std/event/lock.zig b/lib/std/event/lock.zig
index a0b1fd3e50..fdcfd1e298 100644
--- a/lib/std/event/lock.zig
+++ b/lib/std/event/lock.zig
@@ -119,7 +119,7 @@ test "std.event.Lock" {
     // TODO https://github.com/ziglang/zig/issues/1908
     if (builtin.single_threaded) return error.SkipZigTest;
     // TODO https://github.com/ziglang/zig/issues/3251
-    if (std.os.freebsd.is_the_target) return error.SkipZigTest;
+    if (builtin.os == .freebsd) return error.SkipZigTest;
 
     const allocator = std.heap.direct_allocator;
 
diff --git a/lib/std/fs.zig b/lib/std/fs.zig
index 3fdd175e77..5517f6f280 100644
--- a/lib/std/fs.zig
+++ b/lib/std/fs.zig
@@ -255,7 +255,7 @@ pub const AtomicFile = struct {
         assert(!self.finished);
         self.file.close();
         self.finished = true;
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             const dest_path_w = try os.windows.sliceToPrefixedFileW(self.dest_path);
             const tmp_path_w = try os.windows.cStrToPrefixedFileW(&self.tmp_path_buf);
             return os.renameW(&tmp_path_w, &dest_path_w);
@@ -659,7 +659,7 @@ pub const Dir = struct {
     /// Closing the returned `Dir` is checked illegal behavior.
     /// On POSIX targets, this function is comptime-callable.
     pub fn cwd() Dir {
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             return Dir{ .fd = os.windows.peb().ProcessParameters.CurrentDirectory.Handle };
         } else {
             return Dir{ .fd = os.AT_FDCWD };
@@ -711,7 +711,7 @@ pub const Dir = struct {
 
     /// Call `close` on the result when done.
     pub fn openDir(self: Dir, sub_path: []const u8) OpenError!Dir {
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             const sub_path_w = try os.windows.sliceToPrefixedFileW(sub_path);
             return self.openDirW(&sub_path_w);
         }
@@ -722,7 +722,7 @@ pub const Dir = struct {
 
     /// Same as `openDir` except the parameter is null-terminated.
     pub fn openDirC(self: Dir, sub_path_c: [*]const u8) OpenError!Dir {
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             const sub_path_w = try os.windows.cStrToPrefixedFileW(sub_path_c);
             return self.openDirW(&sub_path_w);
         }
@@ -829,7 +829,7 @@ pub const Dir = struct {
     /// Returns `error.DirNotEmpty` if the directory is not empty.
     /// To delete a directory recursively, see `deleteTree`.
     pub fn deleteDir(self: Dir, sub_path: []const u8) DeleteDirError!void {
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             const sub_path_w = try os.windows.sliceToPrefixedFileW(sub_path);
             return self.deleteDirW(&sub_path_w);
         }
@@ -1146,10 +1146,10 @@ pub fn readLinkC(pathname_c: [*]const u8, buffer: *[MAX_PATH_BYTES]u8) ![]u8 {
 pub const OpenSelfExeError = os.OpenError || os.windows.CreateFileError || SelfExePathError;
 
 pub fn openSelfExe() OpenSelfExeError!File {
-    if (os.linux.is_the_target) {
+    if (builtin.os == .linux) {
         return File.openReadC(c"/proc/self/exe");
     }
-    if (os.windows.is_the_target) {
+    if (builtin.os == .windows) {
         var buf: [os.windows.PATH_MAX_WIDE]u16 = undefined;
         const wide_slice = try selfExePathW(&buf);
         return File.openReadW(wide_slice.ptr);
@@ -1180,7 +1180,7 @@ pub const SelfExePathError = os.ReadLinkError || os.SysCtlError;
 /// been deleted, the file path looks something like `/a/b/c/exe (deleted)`.
 /// TODO make the return type of this a null terminated pointer
 pub fn selfExePath(out_buffer: *[MAX_PATH_BYTES]u8) SelfExePathError![]u8 {
-    if (os.darwin.is_the_target) {
+    if (comptime std.Target.current.isDarwin()) {
         var u32_len: u32 = out_buffer.len;
         const rc = std.c._NSGetExecutablePath(out_buffer, &u32_len);
         if (rc != 0) return error.NameTooLong;
@@ -1228,7 +1228,7 @@ pub fn selfExeDirPathAlloc(allocator: *Allocator) ![]u8 {
 /// Get the directory path that contains the current executable.
 /// Returned value is a slice of out_buffer.
 pub fn selfExeDirPath(out_buffer: *[MAX_PATH_BYTES]u8) SelfExePathError![]const u8 {
-    if (os.linux.is_the_target) {
+    if (builtin.os == .linux) {
         // If the currently executing binary has been deleted,
         // the file path looks something like `/a/b/c/exe (deleted)`
         // This path cannot be opened, but it's valid for determining the directory
diff --git a/lib/std/fs/file.zig b/lib/std/fs/file.zig
index 44992ff47d..06a26ed481 100644
--- a/lib/std/fs/file.zig
+++ b/lib/std/fs/file.zig
@@ -27,7 +27,7 @@ pub const File = struct {
 
     /// Call close to clean up.
     pub fn openRead(path: []const u8) OpenError!File {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             const path_w = try windows.sliceToPrefixedFileW(path);
             return openReadW(&path_w);
         }
@@ -37,7 +37,7 @@ pub const File = struct {
 
     /// `openRead` except with a null terminated path
     pub fn openReadC(path: [*]const u8) OpenError!File {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             const path_w = try windows.cStrToPrefixedFileW(path);
             return openReadW(&path_w);
         }
@@ -69,7 +69,7 @@ pub const File = struct {
     /// If a file already exists in the destination it will be truncated.
     /// Call close to clean up.
     pub fn openWriteMode(path: []const u8, file_mode: Mode) OpenError!File {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             const path_w = try windows.sliceToPrefixedFileW(path);
             return openWriteModeW(&path_w, file_mode);
         }
@@ -79,7 +79,7 @@ pub const File = struct {
 
     /// Same as `openWriteMode` except `path` is null-terminated.
     pub fn openWriteModeC(path: [*]const u8, file_mode: Mode) OpenError!File {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             const path_w = try windows.cStrToPrefixedFileW(path);
             return openWriteModeW(&path_w, file_mode);
         }
@@ -106,7 +106,7 @@ pub const File = struct {
     /// If a file already exists in the destination this returns OpenError.PathAlreadyExists
     /// Call close to clean up.
     pub fn openWriteNoClobber(path: []const u8, file_mode: Mode) OpenError!File {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             const path_w = try windows.sliceToPrefixedFileW(path);
             return openWriteNoClobberW(&path_w, file_mode);
         }
@@ -115,7 +115,7 @@ pub const File = struct {
     }
 
     pub fn openWriteNoClobberC(path: [*]const u8, file_mode: Mode) OpenError!File {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             const path_w = try windows.cStrToPrefixedFileW(path);
             return openWriteNoClobberW(&path_w, file_mode);
         }
@@ -174,7 +174,7 @@ pub const File = struct {
 
     /// Test whether ANSI escape codes will be treated as such.
     pub fn supportsAnsiEscapeCodes(self: File) bool {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             return os.isCygwinPty(self.handle);
         }
         if (self.isTty()) {
@@ -214,7 +214,7 @@ pub const File = struct {
     }
 
     pub fn getEndPos(self: File) GetPosError!u64 {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             return windows.GetFileSizeEx(self.handle);
         }
         return (try self.stat()).size;
@@ -223,7 +223,7 @@ pub const File = struct {
     pub const ModeError = os.FStatError;
 
     pub fn mode(self: File) ModeError!Mode {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             return {};
         }
         return (try self.stat()).mode;
@@ -246,7 +246,7 @@ pub const File = struct {
     pub const StatError = os.FStatError;
 
     pub fn stat(self: File) StatError!Stat {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             var io_status_block: windows.IO_STATUS_BLOCK = undefined;
             var info: windows.FILE_ALL_INFORMATION = undefined;
             const rc = windows.ntdll.NtQueryInformationFile(self.handle, &io_status_block, &info, @sizeOf(windows.FILE_ALL_INFORMATION), .FileAllInformation);
@@ -291,7 +291,7 @@ pub const File = struct {
         /// last modification timestamp in nanoseconds
         mtime: i64,
     ) UpdateTimesError!void {
-        if (windows.is_the_target) {
+        if (builtin.os == .windows) {
             const atime_ft = windows.nanoSecondsToFileTime(atime);
             const mtime_ft = windows.nanoSecondsToFileTime(mtime);
             return windows.SetFileTime(self.handle, null, &atime_ft, &mtime_ft);
diff --git a/lib/std/fs/path.zig b/lib/std/fs/path.zig
index 560d9b58f3..f337e1df9a 100644
--- a/lib/std/fs/path.zig
+++ b/lib/std/fs/path.zig
@@ -13,16 +13,16 @@ const process = std.process;
 
 pub const sep_windows = '\\';
 pub const sep_posix = '/';
-pub const sep = if (windows.is_the_target) sep_windows else sep_posix;
+pub const sep = if (builtin.os == .windows) sep_windows else sep_posix;
 
 pub const sep_str = [1]u8{sep};
 
 pub const delimiter_windows = ';';
 pub const delimiter_posix = ':';
-pub const delimiter = if (windows.is_the_target) delimiter_windows else delimiter_posix;
+pub const delimiter = if (builtin.os == .windows) delimiter_windows else delimiter_posix;
 
 pub fn isSep(byte: u8) bool {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return byte == '/' or byte == '\\';
     } else {
         return byte == '/';
@@ -72,7 +72,7 @@ fn joinSep(allocator: *Allocator, separator: u8, paths: []const []const u8) ![]u
     return buf;
 }
 
-pub const join = if (windows.is_the_target) joinWindows else joinPosix;
+pub const join = if (builtin.os == .windows) joinWindows else joinPosix;
 
 /// Naively combines a series of paths with the native path seperator.
 /// Allocates memory for the result, which must be freed by the caller.
@@ -129,7 +129,7 @@ test "join" {
 }
 
 pub fn isAbsolute(path: []const u8) bool {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return isAbsoluteWindows(path);
     } else {
         return isAbsolutePosix(path);
@@ -327,7 +327,7 @@ test "windowsParsePath" {
 }
 
 pub fn diskDesignator(path: []const u8) []const u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return diskDesignatorWindows(path);
     } else {
         return "";
@@ -392,7 +392,7 @@ fn asciiEqlIgnoreCase(s1: []const u8, s2: []const u8) bool {
 
 /// On Windows, this calls `resolveWindows` and on POSIX it calls `resolvePosix`.
 pub fn resolve(allocator: *Allocator, paths: []const []const u8) ![]u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return resolveWindows(allocator, paths);
     } else {
         return resolvePosix(allocator, paths);
@@ -409,7 +409,7 @@ pub fn resolve(allocator: *Allocator, paths: []const []const u8) ![]u8 {
 /// Without performing actual syscalls, resolving `..` could be incorrect.
 pub fn resolveWindows(allocator: *Allocator, paths: []const []const u8) ![]u8 {
     if (paths.len == 0) {
-        assert(windows.is_the_target); // resolveWindows called on non windows can't use getCwd
+        assert(builtin.os == .windows); // resolveWindows called on non windows can't use getCwd
         return process.getCwdAlloc(allocator);
     }
 
@@ -504,7 +504,7 @@ pub fn resolveWindows(allocator: *Allocator, paths: []const []const u8) ![]u8 {
                 result_disk_designator = result[0..result_index];
             },
             WindowsPath.Kind.None => {
-                assert(windows.is_the_target); // resolveWindows called on non windows can't use getCwd
+                assert(builtin.os == .windows); // resolveWindows called on non windows can't use getCwd
                 const cwd = try process.getCwdAlloc(allocator);
                 defer allocator.free(cwd);
                 const parsed_cwd = windowsParsePath(cwd);
@@ -519,7 +519,7 @@ pub fn resolveWindows(allocator: *Allocator, paths: []const []const u8) ![]u8 {
             },
         }
     } else {
-        assert(windows.is_the_target); // resolveWindows called on non windows can't use getCwd
+        assert(builtin.os == .windows); // resolveWindows called on non windows can't use getCwd
         // TODO call get cwd for the result_disk_designator instead of the global one
         const cwd = try process.getCwdAlloc(allocator);
         defer allocator.free(cwd);
@@ -590,7 +590,7 @@ pub fn resolveWindows(allocator: *Allocator, paths: []const []const u8) ![]u8 {
 /// Without performing actual syscalls, resolving `..` could be incorrect.
 pub fn resolvePosix(allocator: *Allocator, paths: []const []const u8) ![]u8 {
     if (paths.len == 0) {
-        assert(!windows.is_the_target); // resolvePosix called on windows can't use getCwd
+        assert(builtin.os != .windows); // resolvePosix called on windows can't use getCwd
         return process.getCwdAlloc(allocator);
     }
 
@@ -612,7 +612,7 @@ pub fn resolvePosix(allocator: *Allocator, paths: []const []const u8) ![]u8 {
     if (have_abs) {
         result = try allocator.alloc(u8, max_size);
     } else {
-        assert(!windows.is_the_target); // resolvePosix called on windows can't use getCwd
+        assert(builtin.os != .windows); // resolvePosix called on windows can't use getCwd
         const cwd = try process.getCwdAlloc(allocator);
         defer allocator.free(cwd);
         result = try allocator.alloc(u8, max_size + cwd.len + 1);
@@ -653,7 +653,7 @@ pub fn resolvePosix(allocator: *Allocator, paths: []const []const u8) ![]u8 {
 
 test "resolve" {
     const cwd = try process.getCwdAlloc(debug.global_allocator);
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         if (windowsParsePath(cwd).kind == WindowsPath.Kind.Drive) {
             cwd[0] = asciiUpper(cwd[0]);
         }
@@ -669,7 +669,7 @@ test "resolveWindows" {
         // TODO https://github.com/ziglang/zig/issues/3288
         return error.SkipZigTest;
     }
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const cwd = try process.getCwdAlloc(debug.global_allocator);
         const parsed_cwd = windowsParsePath(cwd);
         {
@@ -735,7 +735,7 @@ fn testResolvePosix(paths: []const []const u8) []u8 {
 /// If the path is a file in the current directory (no directory component)
 /// then returns null
 pub fn dirname(path: []const u8) ?[]const u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return dirnameWindows(path);
     } else {
         return dirnamePosix(path);
@@ -867,7 +867,7 @@ fn testDirnameWindows(input: []const u8, expected_output: ?[]const u8) void {
 }
 
 pub fn basename(path: []const u8) []const u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return basenameWindows(path);
     } else {
         return basenamePosix(path);
@@ -983,7 +983,7 @@ fn testBasenameWindows(input: []const u8, expected_output: []const u8) void {
 /// string is returned.
 /// On Windows this canonicalizes the drive to a capital letter and paths to `\\`.
 pub fn relative(allocator: *Allocator, from: []const u8, to: []const u8) ![]u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return relativeWindows(allocator, from, to);
     } else {
         return relativePosix(allocator, from, to);
diff --git a/lib/std/heap.zig b/lib/std/heap.zig
index f3a0d457d2..8723c7eab6 100644
--- a/lib/std/heap.zig
+++ b/lib/std/heap.zig
@@ -44,7 +44,7 @@ const DirectAllocator = struct {
         if (n == 0)
             return (([*]u8)(undefined))[0..0];
 
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             const w = os.windows;
 
             // Although officially it's at least aligned to page boundary,
@@ -130,7 +130,7 @@ const DirectAllocator = struct {
 
     fn shrink(allocator: *Allocator, old_mem_unaligned: []u8, old_align: u29, new_size: usize, new_align: u29) []u8 {
         const old_mem = @alignCast(mem.page_size, old_mem_unaligned);
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             const w = os.windows;
             if (new_size == 0) {
                 // From the docs:
@@ -170,7 +170,7 @@ const DirectAllocator = struct {
 
     fn realloc(allocator: *Allocator, old_mem_unaligned: []u8, old_align: u29, new_size: usize, new_align: u29) ![]u8 {
         const old_mem = @alignCast(mem.page_size, old_mem_unaligned);
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             if (old_mem.len == 0) {
                 return alloc(allocator, new_size, new_align);
             }
diff --git a/lib/std/io.zig b/lib/std/io.zig
index 7502601650..39c3a7cf9b 100644
--- a/lib/std/io.zig
+++ b/lib/std/io.zig
@@ -37,7 +37,7 @@ pub const is_async = mode != .blocking;
 pub const GetStdIoError = os.windows.GetStdHandleError;
 
 pub fn getStdOut() GetStdIoError!File {
-    if (os.windows.is_the_target) {
+    if (builtin.os == .windows) {
         const handle = try os.windows.GetStdHandle(os.windows.STD_OUTPUT_HANDLE);
         return File.openHandle(handle);
     }
@@ -45,7 +45,7 @@ pub fn getStdOut() GetStdIoError!File {
 }
 
 pub fn getStdErr() GetStdIoError!File {
-    if (os.windows.is_the_target) {
+    if (builtin.os == .windows) {
         const handle = try os.windows.GetStdHandle(os.windows.STD_ERROR_HANDLE);
         return File.openHandle(handle);
     }
@@ -53,7 +53,7 @@ pub fn getStdErr() GetStdIoError!File {
 }
 
 pub fn getStdIn() GetStdIoError!File {
-    if (os.windows.is_the_target) {
+    if (builtin.os == .windows) {
         const handle = try os.windows.GetStdHandle(os.windows.STD_INPUT_HANDLE);
         return File.openHandle(handle);
     }
diff --git a/lib/std/os.zig b/lib/std/os.zig
index 4a2c0b971e..d239f198f4 100644
--- a/lib/std/os.zig
+++ b/lib/std/os.zig
@@ -85,13 +85,13 @@ pub const errno = system.getErrno;
 /// must call `fsync` before `close`.
 /// Note: The Zig standard library does not support POSIX thread cancellation.
 pub fn close(fd: fd_t) void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.CloseHandle(fd);
     }
-    if (wasi.is_the_target) {
+    if (builtin.os == .wasi) {
         _ = wasi.fd_close(fd);
     }
-    if (darwin.is_the_target) {
+    if (comptime std.Target.current.isDarwin()) {
         // This avoids the EINTR problem.
         switch (darwin.getErrno(darwin.@"close$NOCANCEL"(fd))) {
             EBADF => unreachable, // Always a race condition.
@@ -113,12 +113,12 @@ pub const GetRandomError = OpenError;
 /// appropriate OS-specific library call. Otherwise it uses the zig standard
 /// library implementation.
 pub fn getrandom(buffer: []u8) GetRandomError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.RtlGenRandom(buffer);
     }
-    if (linux.is_the_target or freebsd.is_the_target) {
+    if (builtin.os == .linux or builtin.os == .freebsd) {
         var buf = buffer;
-        const use_c = !linux.is_the_target or
+        const use_c = builtin.os != .linux or
             std.c.versionCheck(builtin.Version{ .major = 2, .minor = 25, .patch = 0 }).ok;
 
         while (buf.len != 0) {
@@ -145,7 +145,7 @@ pub fn getrandom(buffer: []u8) GetRandomError!void {
         }
         return;
     }
-    if (wasi.is_the_target) {
+    if (builtin.os == .wasi) {
         switch (wasi.random_get(buffer.ptr, buffer.len)) {
             0 => return,
             else => |err| return unexpectedErrno(err),
@@ -175,7 +175,7 @@ pub fn abort() noreturn {
     // MSVCRT abort() sometimes opens a popup window which is undesirable, so
     // even when linking libc on Windows we use our own abort implementation.
     // See https://github.com/ziglang/zig/issues/2071 for more details.
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         if (builtin.mode == .Debug) {
             @breakpoint();
         }
@@ -206,14 +206,14 @@ pub fn raise(sig: u8) RaiseError!void {
         }
     }
 
-    if (wasi.is_the_target) {
+    if (builtin.os == .wasi) {
         switch (wasi.proc_raise(SIGABRT)) {
             0 => return,
             else => |err| return unexpectedErrno(err),
         }
     }
 
-    if (linux.is_the_target) {
+    if (builtin.os == .linux) {
         var set: linux.sigset_t = undefined;
         linux.blockAppSignals(&set);
         const tid = linux.syscall0(linux.SYS_gettid);
@@ -245,16 +245,16 @@ pub fn exit(status: u8) noreturn {
     if (builtin.link_libc) {
         system.exit(status);
     }
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         windows.kernel32.ExitProcess(status);
     }
-    if (wasi.is_the_target) {
+    if (builtin.os == .wasi) {
         wasi.proc_exit(status);
     }
-    if (linux.is_the_target and !builtin.single_threaded) {
+    if (builtin.os == .linux and !builtin.single_threaded) {
         linux.exit_group(status);
     }
-    if (uefi.is_the_target) {
+    if (builtin.os == .uefi) {
         // exit() is only avaliable if exitBootServices() has not been called yet.
         // This call to exit should not fail, so we don't care about its return value.
         if (uefi.system_table.boot_services) |bs| {
@@ -283,11 +283,11 @@ pub const ReadError = error{
 /// If the application has a global event loop enabled, EAGAIN is handled
 /// via the event loop. Otherwise EAGAIN results in error.WouldBlock.
 pub fn read(fd: fd_t, buf: []u8) ReadError!usize {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.ReadFile(fd, buf);
     }
 
-    if (wasi.is_the_target and !builtin.link_libc) {
+    if (builtin.os == .wasi and !builtin.link_libc) {
         const iovs = [1]iovec{iovec{
             .iov_base = buf.ptr,
             .iov_len = buf.len,
@@ -327,7 +327,7 @@ pub fn read(fd: fd_t, buf: []u8) ReadError!usize {
 /// Number of bytes read is returned. Upon reading end-of-file, zero is returned.
 /// This function is for blocking file descriptors only.
 pub fn preadv(fd: fd_t, iov: []const iovec, offset: u64) ReadError!usize {
-    if (darwin.is_the_target) {
+    if (comptime std.Target.current.isDarwin()) {
         // Darwin does not have preadv but it does have pread.
         var off: usize = 0;
         var iov_i: usize = 0;
@@ -398,11 +398,11 @@ pub const WriteError = error{
 /// Write to a file descriptor. Keeps trying if it gets interrupted.
 /// This function is for blocking file descriptors only.
 pub fn write(fd: fd_t, bytes: []const u8) WriteError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.WriteFile(fd, bytes);
     }
 
-    if (wasi.is_the_target and !builtin.link_libc) {
+    if (builtin.os == .wasi and !builtin.link_libc) {
         const ciovs = [1]iovec_const{iovec_const{
             .iov_base = bytes.ptr,
             .iov_len = bytes.len,
@@ -477,7 +477,7 @@ pub fn writev(fd: fd_t, iov: []const iovec_const) WriteError!void {
 /// This function is for blocking file descriptors only. For non-blocking, see
 /// `pwritevAsync`.
 pub fn pwritev(fd: fd_t, iov: []const iovec_const, offset: u64) WriteError!void {
-    if (darwin.is_the_target) {
+    if (comptime std.Target.current.isDarwin()) {
         // Darwin does not have pwritev but it does have pwrite.
         var off: usize = 0;
         var iov_i: usize = 0;
@@ -841,7 +841,7 @@ pub const GetCwdError = error{
 
 /// The result is a slice of out_buffer, indexed from 0.
 pub fn getcwd(out_buffer: []u8) GetCwdError![]u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.GetCurrentDirectory(out_buffer);
     }
 
@@ -882,7 +882,7 @@ pub const SymLinkError = error{
 /// If `sym_link_path` exists, it will not be overwritten.
 /// See also `symlinkC` and `symlinkW`.
 pub fn symlink(target_path: []const u8, sym_link_path: []const u8) SymLinkError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const target_path_w = try windows.sliceToPrefixedFileW(target_path);
         const sym_link_path_w = try windows.sliceToPrefixedFileW(sym_link_path);
         return windows.CreateSymbolicLinkW(&sym_link_path_w, &target_path_w, 0);
@@ -896,7 +896,7 @@ pub fn symlink(target_path: []const u8, sym_link_path: []const u8) SymLinkError!
 /// This is the same as `symlink` except the parameters are null-terminated pointers.
 /// See also `symlink`.
 pub fn symlinkC(target_path: [*]const u8, sym_link_path: [*]const u8) SymLinkError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const target_path_w = try windows.cStrToPrefixedFileW(target_path);
         const sym_link_path_w = try windows.cStrToPrefixedFileW(sym_link_path);
         return windows.CreateSymbolicLinkW(&sym_link_path_w, &target_path_w, 0);
@@ -971,7 +971,7 @@ pub const UnlinkError = error{
 /// Delete a name and possibly the file it refers to.
 /// See also `unlinkC`.
 pub fn unlink(file_path: []const u8) UnlinkError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const file_path_w = try windows.sliceToPrefixedFileW(file_path);
         return windows.DeleteFileW(&file_path_w);
     } else {
@@ -982,7 +982,7 @@ pub fn unlink(file_path: []const u8) UnlinkError!void {
 
 /// Same as `unlink` except the parameter is a null terminated UTF8-encoded string.
 pub fn unlinkC(file_path: [*]const u8) UnlinkError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const file_path_w = try windows.cStrToPrefixedFileW(file_path);
         return windows.DeleteFileW(&file_path_w);
     }
@@ -1012,7 +1012,7 @@ pub const UnlinkatError = UnlinkError || error{
 
 /// Delete a file name and possibly the file it refers to, based on an open directory handle.
 pub fn unlinkat(dirfd: fd_t, file_path: []const u8, flags: u32) UnlinkatError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const file_path_w = try windows.sliceToPrefixedFileW(file_path);
         return unlinkatW(dirfd, &file_path_w, flags);
     }
@@ -1022,7 +1022,7 @@ pub fn unlinkat(dirfd: fd_t, file_path: []const u8, flags: u32) UnlinkatError!vo
 
 /// Same as `unlinkat` but `file_path` is a null-terminated string.
 pub fn unlinkatC(dirfd: fd_t, file_path_c: [*]const u8, flags: u32) UnlinkatError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const file_path_w = try windows.cStrToPrefixedFileW(file_path_c);
         return unlinkatW(dirfd, &file_path_w, flags);
     }
@@ -1133,7 +1133,7 @@ const RenameError = error{
 
 /// Change the name or location of a file.
 pub fn rename(old_path: []const u8, new_path: []const u8) RenameError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const old_path_w = try windows.sliceToPrefixedFileW(old_path);
         const new_path_w = try windows.sliceToPrefixedFileW(new_path);
         return renameW(&old_path_w, &new_path_w);
@@ -1146,7 +1146,7 @@ pub fn rename(old_path: []const u8, new_path: []const u8) RenameError!void {
 
 /// Same as `rename` except the parameters are null-terminated byte arrays.
 pub fn renameC(old_path: [*]const u8, new_path: [*]const u8) RenameError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const old_path_w = try windows.cStrToPrefixedFileW(old_path);
         const new_path_w = try windows.cStrToPrefixedFileW(new_path);
         return renameW(&old_path_w, &new_path_w);
@@ -1201,7 +1201,7 @@ pub const MakeDirError = error{
 /// Create a directory.
 /// `mode` is ignored on Windows.
 pub fn mkdir(dir_path: []const u8, mode: u32) MakeDirError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const dir_path_w = try windows.sliceToPrefixedFileW(dir_path);
         return windows.CreateDirectoryW(&dir_path_w, null);
     } else {
@@ -1212,7 +1212,7 @@ pub fn mkdir(dir_path: []const u8, mode: u32) MakeDirError!void {
 
 /// Same as `mkdir` but the parameter is a null-terminated UTF8-encoded string.
 pub fn mkdirC(dir_path: [*]const u8, mode: u32) MakeDirError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const dir_path_w = try windows.cStrToPrefixedFileW(dir_path);
         return windows.CreateDirectoryW(&dir_path_w, null);
     }
@@ -1251,7 +1251,7 @@ pub const DeleteDirError = error{
 
 /// Deletes an empty directory.
 pub fn rmdir(dir_path: []const u8) DeleteDirError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const dir_path_w = try windows.sliceToPrefixedFileW(dir_path);
         return windows.RemoveDirectoryW(&dir_path_w);
     } else {
@@ -1262,7 +1262,7 @@ pub fn rmdir(dir_path: []const u8) DeleteDirError!void {
 
 /// Same as `rmdir` except the parameter is null-terminated.
 pub fn rmdirC(dir_path: [*]const u8) DeleteDirError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const dir_path_w = try windows.cStrToPrefixedFileW(dir_path);
         return windows.RemoveDirectoryW(&dir_path_w);
     }
@@ -1298,7 +1298,7 @@ pub const ChangeCurDirError = error{
 /// Changes the current working directory of the calling process.
 /// `dir_path` is recommended to be a UTF-8 encoded string.
 pub fn chdir(dir_path: []const u8) ChangeCurDirError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const dir_path_w = try windows.sliceToPrefixedFileW(dir_path);
         @compileError("TODO implement chdir for Windows");
     } else {
@@ -1309,7 +1309,7 @@ pub fn chdir(dir_path: []const u8) ChangeCurDirError!void {
 
 /// Same as `chdir` except the parameter is null-terminated.
 pub fn chdirC(dir_path: [*]const u8) ChangeCurDirError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const dir_path_w = try windows.cStrToPrefixedFileW(dir_path);
         @compileError("TODO implement chdir for Windows");
     }
@@ -1340,7 +1340,7 @@ pub const ReadLinkError = error{
 /// Read value of a symbolic link.
 /// The return value is a slice of `out_buffer` from index 0.
 pub fn readlink(file_path: []const u8, out_buffer: []u8) ReadLinkError![]u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const file_path_w = try windows.sliceToPrefixedFileW(file_path);
         @compileError("TODO implement readlink for Windows");
     } else {
@@ -1351,7 +1351,7 @@ pub fn readlink(file_path: []const u8, out_buffer: []u8) ReadLinkError![]u8 {
 
 /// Same as `readlink` except `file_path` is null-terminated.
 pub fn readlinkC(file_path: [*]const u8, out_buffer: []u8) ReadLinkError![]u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const file_path_w = try windows.cStrToPrefixedFileW(file_path);
         @compileError("TODO implement readlink for Windows");
     }
@@ -1372,7 +1372,7 @@ pub fn readlinkC(file_path: [*]const u8, out_buffer: []u8) ReadLinkError![]u8 {
 }
 
 pub fn readlinkatC(dirfd: fd_t, file_path: [*]const u8, out_buffer: []u8) ReadLinkError![]u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const file_path_w = try windows.cStrToPrefixedFileW(file_path);
         @compileError("TODO implement readlink for Windows");
     }
@@ -1440,7 +1440,7 @@ pub fn setregid(rgid: u32, egid: u32) SetIdError!void {
 
 /// Test whether a file descriptor refers to a terminal.
 pub fn isatty(handle: fd_t) bool {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         if (isCygwinPty(handle))
             return true;
 
@@ -1450,10 +1450,10 @@ pub fn isatty(handle: fd_t) bool {
     if (builtin.link_libc) {
         return system.isatty(handle) != 0;
     }
-    if (wasi.is_the_target) {
+    if (builtin.os == .wasi) {
         @compileError("TODO implement std.os.isatty for WASI");
     }
-    if (linux.is_the_target) {
+    if (builtin.os == .linux) {
         var wsz: linux.winsize = undefined;
         return linux.syscall3(linux.SYS_ioctl, @bitCast(usize, isize(handle)), linux.TIOCGWINSZ, @ptrToInt(&wsz)) == 0;
     }
@@ -1461,7 +1461,7 @@ pub fn isatty(handle: fd_t) bool {
 }
 
 pub fn isCygwinPty(handle: fd_t) bool {
-    if (!windows.is_the_target) return false;
+    if (builtin.os != .windows) return false;
 
     const size = @sizeOf(windows.FILE_NAME_INFO);
     var name_info_bytes align(@alignOf(windows.FILE_NAME_INFO)) = [_]u8{0} ** (size + windows.MAX_PATH);
@@ -1961,7 +1961,7 @@ pub const FStatError = error{SystemResources} || UnexpectedError;
 
 pub fn fstat(fd: fd_t) FStatError!Stat {
     var stat: Stat = undefined;
-    if (darwin.is_the_target) {
+    if (comptime std.Target.current.isDarwin()) {
         switch (darwin.getErrno(darwin.@"fstat$INODE64"(fd, &stat))) {
             0 => return stat,
             EINVAL => unreachable,
@@ -2227,7 +2227,7 @@ pub const AccessError = error{
 /// check user's permissions for a file
 /// TODO currently this assumes `mode` is `F_OK` on Windows.
 pub fn access(path: []const u8, mode: u32) AccessError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const path_w = try windows.sliceToPrefixedFileW(path);
         _ = try windows.GetFileAttributesW(&path_w);
         return;
@@ -2238,7 +2238,7 @@ pub fn access(path: []const u8, mode: u32) AccessError!void {
 
 /// Same as `access` except `path` is null-terminated.
 pub fn accessC(path: [*]const u8, mode: u32) AccessError!void {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const path_w = try windows.cStrToPrefixedFileW(path);
         _ = try windows.GetFileAttributesW(&path_w);
         return;
@@ -2358,7 +2358,7 @@ pub const SeekError = error{Unseekable} || UnexpectedError;
 
 /// Repositions read/write file offset relative to the beginning.
 pub fn lseek_SET(fd: fd_t, offset: u64) SeekError!void {
-    if (linux.is_the_target and !builtin.link_libc and @sizeOf(usize) == 4) {
+    if (builtin.os == .linux and !builtin.link_libc and @sizeOf(usize) == 4) {
         var result: u64 = undefined;
         switch (errno(system.llseek(fd, offset, &result, SEEK_SET))) {
             0 => return,
@@ -2370,7 +2370,7 @@ pub fn lseek_SET(fd: fd_t, offset: u64) SeekError!void {
             else => |err| return unexpectedErrno(err),
         }
     }
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.SetFilePointerEx_BEGIN(fd, offset);
     }
     const ipos = @bitCast(i64, offset); // the OS treats this as unsigned
@@ -2387,7 +2387,7 @@ pub fn lseek_SET(fd: fd_t, offset: u64) SeekError!void {
 
 /// Repositions read/write file offset relative to the current offset.
 pub fn lseek_CUR(fd: fd_t, offset: i64) SeekError!void {
-    if (linux.is_the_target and !builtin.link_libc and @sizeOf(usize) == 4) {
+    if (builtin.os == .linux and !builtin.link_libc and @sizeOf(usize) == 4) {
         var result: u64 = undefined;
         switch (errno(system.llseek(fd, @bitCast(u64, offset), &result, SEEK_CUR))) {
             0 => return,
@@ -2399,7 +2399,7 @@ pub fn lseek_CUR(fd: fd_t, offset: i64) SeekError!void {
             else => |err| return unexpectedErrno(err),
         }
     }
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.SetFilePointerEx_CURRENT(fd, offset);
     }
     switch (errno(system.lseek(fd, offset, SEEK_CUR))) {
@@ -2415,7 +2415,7 @@ pub fn lseek_CUR(fd: fd_t, offset: i64) SeekError!void {
 
 /// Repositions read/write file offset relative to the end.
 pub fn lseek_END(fd: fd_t, offset: i64) SeekError!void {
-    if (linux.is_the_target and !builtin.link_libc and @sizeOf(usize) == 4) {
+    if (builtin.os == .linux and !builtin.link_libc and @sizeOf(usize) == 4) {
         var result: u64 = undefined;
         switch (errno(system.llseek(fd, @bitCast(u64, offset), &result, SEEK_END))) {
             0 => return,
@@ -2427,7 +2427,7 @@ pub fn lseek_END(fd: fd_t, offset: i64) SeekError!void {
             else => |err| return unexpectedErrno(err),
         }
     }
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.SetFilePointerEx_END(fd, offset);
     }
     switch (errno(system.lseek(fd, offset, SEEK_END))) {
@@ -2443,7 +2443,7 @@ pub fn lseek_END(fd: fd_t, offset: i64) SeekError!void {
 
 /// Returns the read/write file offset relative to the beginning.
 pub fn lseek_CUR_get(fd: fd_t) SeekError!u64 {
-    if (linux.is_the_target and !builtin.link_libc and @sizeOf(usize) == 4) {
+    if (builtin.os == .linux and !builtin.link_libc and @sizeOf(usize) == 4) {
         var result: u64 = undefined;
         switch (errno(system.llseek(fd, 0, &result, SEEK_CUR))) {
             0 => return result,
@@ -2455,7 +2455,7 @@ pub fn lseek_CUR_get(fd: fd_t) SeekError!u64 {
             else => |err| return unexpectedErrno(err),
         }
     }
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         return windows.SetFilePointerEx_CURRENT_get(fd);
     }
     const rc = system.lseek(fd, 0, SEEK_CUR);
@@ -2504,7 +2504,7 @@ pub const RealPathError = error{
 /// The return value is a slice of `out_buffer`, but not necessarily from the beginning.
 /// See also `realpathC` and `realpathW`.
 pub fn realpath(pathname: []const u8, out_buffer: *[MAX_PATH_BYTES]u8) RealPathError![]u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const pathname_w = try windows.sliceToPrefixedFileW(pathname);
         return realpathW(&pathname_w, out_buffer);
     }
@@ -2514,11 +2514,11 @@ pub fn realpath(pathname: []const u8, out_buffer: *[MAX_PATH_BYTES]u8) RealPathE
 
 /// Same as `realpath` except `pathname` is null-terminated.
 pub fn realpathC(pathname: [*]const u8, out_buffer: *[MAX_PATH_BYTES]u8) RealPathError![]u8 {
-    if (windows.is_the_target) {
+    if (builtin.os == .windows) {
         const pathname_w = try windows.cStrToPrefixedFileW(pathname);
         return realpathW(&pathname_w, out_buffer);
     }
-    if (linux.is_the_target and !builtin.link_libc) {
+    if (builtin.os == .linux and !builtin.link_libc) {
         const fd = try openC(pathname, linux.O_PATH | linux.O_NONBLOCK | linux.O_CLOEXEC, 0);
         defer close(fd);
 
@@ -2596,9 +2596,12 @@ pub fn nanosleep(seconds: u64, nanoseconds: u64) void {
     }
 }
 
-pub fn dl_iterate_phdr(comptime T: type, callback: extern fn (info: *dl_phdr_info, size: usize, data: ?*T) i32, data: ?*T) isize {
-    // This is implemented only for systems using ELF executables
-    if (windows.is_the_target or builtin.os == .uefi or wasi.is_the_target or darwin.is_the_target)
+pub fn dl_iterate_phdr(
+    comptime T: type,
+    callback: extern fn (info: *dl_phdr_info, size: usize, data: ?*T) i32,
+    data: ?*T,
+) isize {
+    if (builtin.object_format != .elf)
         @compileError("dl_iterate_phdr is not available for this target");
 
     if (builtin.link_libc) {
@@ -2737,7 +2740,7 @@ pub const SigaltstackError = error{
 } || UnexpectedError;
 
 pub fn sigaltstack(ss: ?*stack_t, old_ss: ?*stack_t) SigaltstackError!void {
-    if (windows.is_the_target or uefi.is_the_target or wasi.is_the_target)
+    if (builtin.os == .windows or builtin.os == .uefi or builtin.os == .wasi)
         @compileError("std.os.sigaltstack not available for this target");
 
     switch (errno(system.sigaltstack(ss, old_ss))) {
@@ -2809,7 +2812,7 @@ pub fn gethostname(name_buffer: *[HOST_NAME_MAX]u8) GetHostNameError![]u8 {
             else => |err| return unexpectedErrno(err),
         }
     }
-    if (linux.is_the_target) {
+    if (builtin.os == .linux) {
         var uts: utsname = undefined;
         switch (errno(system.uname(&uts))) {
             0 => {
diff --git a/lib/std/os/darwin.zig b/lib/std/os/darwin.zig
index 0adf71affb..d3e9cefb86 100644
--- a/lib/std/os/darwin.zig
+++ b/lib/std/os/darwin.zig
@@ -1,8 +1,4 @@
 const builtin = @import("builtin");
 const std = @import("../std.zig");
-pub const is_the_target = switch (builtin.os) {
-    .macosx, .tvos, .watchos, .ios => true,
-    else => false,
-};
 pub usingnamespace std.c;
 pub usingnamespace @import("bits.zig");
diff --git a/lib/std/os/freebsd.zig b/lib/std/os/freebsd.zig
index ddbf98f2bc..5f9684b96d 100644
--- a/lib/std/os/freebsd.zig
+++ b/lib/std/os/freebsd.zig
@@ -1,5 +1,3 @@
 const std = @import("../std.zig");
-const builtin = @import("builtin");
-pub const is_the_target = builtin.os == .freebsd;
 pub usingnamespace std.c;
 pub usingnamespace @import("bits.zig");
diff --git a/lib/std/os/linux.zig b/lib/std/os/linux.zig
index c91b6ad98b..2c8500574d 100644
--- a/lib/std/os/linux.zig
+++ b/lib/std/os/linux.zig
@@ -13,7 +13,6 @@ const elf = std.elf;
 const vdso = @import("linux/vdso.zig");
 const dl = @import("../dynamic_library.zig");
 
-pub const is_the_target = builtin.os == .linux;
 pub usingnamespace switch (builtin.arch) {
     .x86_64 => @import("linux/x86_64.zig"),
     .aarch64 => @import("linux/arm64.zig"),
@@ -1079,7 +1078,7 @@ pub fn io_uring_register(fd: i32, opcode: u32, arg: ?*const c_void, nr_args: u32
 }
 
 test "" {
-    if (is_the_target) {
+    if (builtin.os == .linux) {
         _ = @import("linux/test.zig");
     }
 }
diff --git a/lib/std/os/netbsd.zig b/lib/std/os/netbsd.zig
index d484e7374b..5f9684b96d 100644
--- a/lib/std/os/netbsd.zig
+++ b/lib/std/os/netbsd.zig
@@ -1,5 +1,3 @@
-const builtin = @import("builtin");
 const std = @import("../std.zig");
-pub const is_the_target = builtin.os == .netbsd;
 pub usingnamespace std.c;
 pub usingnamespace @import("bits.zig");
diff --git a/lib/std/os/test.zig b/lib/std/os/test.zig
index b6e6728142..1d61548396 100644
--- a/lib/std/os/test.zig
+++ b/lib/std/os/test.zig
@@ -53,7 +53,7 @@ test "std.Thread.getCurrentId" {
     thread.wait();
     if (Thread.use_pthreads) {
         expect(thread_current_id == thread_id);
-    } else if (os.windows.is_the_target) {
+    } else if (builtin.os == .windows) {
         expect(Thread.getCurrentId() != thread_current_id);
     } else {
         // If the thread completes very quickly, then thread_id can be 0. See the
@@ -212,7 +212,7 @@ test "dl_iterate_phdr" {
 }
 
 test "gethostname" {
-    if (os.windows.is_the_target)
+    if (builtin.os == .windows)
         return error.SkipZigTest;
 
     var buf: [os.HOST_NAME_MAX]u8 = undefined;
@@ -221,7 +221,7 @@ test "gethostname" {
 }
 
 test "pipe" {
-    if (os.windows.is_the_target)
+    if (builtin.os == .windows)
         return error.SkipZigTest;
 
     var fds = try os.pipe();
diff --git a/lib/std/os/uefi.zig b/lib/std/os/uefi.zig
index f42dae5fad..31d4d2ed50 100644
--- a/lib/std/os/uefi.zig
+++ b/lib/std/os/uefi.zig
@@ -1,16 +1,15 @@
 /// A protocol is an interface identified by a GUID.
 pub const protocols = @import("uefi/protocols.zig");
+
 /// Status codes returned by EFI interfaces
 pub const status = @import("uefi/status.zig");
 pub const tables = @import("uefi/tables.zig");
 
 const fmt = @import("std").fmt;
 
-const builtin = @import("builtin");
-pub const is_the_target = builtin.os == .uefi;
-
 /// The EFI image's handle that is passed to its entry point.
 pub var handle: Handle = undefined;
+
 /// A pointer to the EFI System Table that is passed to the EFI image's entry point.
 pub var system_table: *tables.SystemTable = undefined;
 
@@ -50,26 +49,35 @@ pub const Handle = *@OpaqueType();
 pub const Time = extern struct {
     /// 1900 - 9999
     year: u16,
+
     /// 1 - 12
     month: u8,
+
     /// 1 - 31
     day: u8,
+
     /// 0 - 23
     hour: u8,
+
     /// 0 - 59
     minute: u8,
+
     /// 0 - 59
     second: u8,
     _pad1: u8,
+
     /// 0 - 999999999
     nanosecond: u32,
+
     /// The time's offset in minutes from UTC.
     /// Allowed values are -1440 to 1440 or unspecified_timezone
     timezone: i16,
     daylight: packed struct {
         _pad1: u6,
+
         /// If true, the time has been adjusted for daylight savings time.
         in_daylight: bool,
+
         /// If true, the time is affected by daylight savings time.
         adjust_daylight: bool,
     },
@@ -83,8 +91,10 @@ pub const Time = extern struct {
 pub const TimeCapabilities = extern struct {
     /// Resolution in Hz
     resolution: u32,
+
     /// Accuracy in an error rate of 1e-6 parts per million.
     accuracy: u32,
+
     /// If true, a time set operation clears the device's time below the resolution level.
     sets_to_zero: bool,
 };
diff --git a/lib/std/os/wasi.zig b/lib/std/os/wasi.zig
index 57b708395c..fce29ef0b3 100644
--- a/lib/std/os/wasi.zig
+++ b/lib/std/os/wasi.zig
@@ -1,10 +1,8 @@
 // Based on https://github.com/CraneStation/wasi-sysroot/blob/wasi/libc-bottom-half/headers/public/wasi/core.h
 // and https://github.com/WebAssembly/WASI/blob/master/design/WASI-core.md
-const builtin = @import("builtin");
 const std = @import("std");
 const assert = std.debug.assert;
 
-pub const is_the_target = builtin.os == .wasi;
 pub usingnamespace @import("bits.zig");
 
 comptime {
diff --git a/lib/std/os/windows.zig b/lib/std/os/windows.zig
index f9753dc2a4..c8c99c6a59 100644
--- a/lib/std/os/windows.zig
+++ b/lib/std/os/windows.zig
@@ -11,7 +11,6 @@ const assert = std.debug.assert;
 const math = std.math;
 const maxInt = std.math.maxInt;
 
-pub const is_the_target = builtin.os == .windows;
 pub const advapi32 = @import("windows/advapi32.zig");
 pub const kernel32 = @import("windows/kernel32.zig");
 pub const ntdll = @import("windows/ntdll.zig");
diff --git a/lib/std/process.zig b/lib/std/process.zig
index c74e8c43be..fca10a240d 100644
--- a/lib/std/process.zig
+++ b/lib/std/process.zig
@@ -39,7 +39,7 @@ pub fn getEnvMap(allocator: *Allocator) !BufMap {
     var result = BufMap.init(allocator);
     errdefer result.deinit();
 
-    if (os.windows.is_the_target) {
+    if (builtin.os == .windows) {
         const ptr = try os.windows.GetEnvironmentStringsW();
         defer os.windows.FreeEnvironmentStringsW(ptr);
 
@@ -129,7 +129,7 @@ pub const GetEnvVarOwnedError = error{
 /// Caller must free returned memory.
 /// TODO make this go through libc when we have it
 pub fn getEnvVarOwned(allocator: *mem.Allocator, key: []const u8) GetEnvVarOwnedError![]u8 {
-    if (os.windows.is_the_target) {
+    if (builtin.os == .windows) {
         const key_with_null = try std.unicode.utf8ToUtf16LeWithNull(allocator, key);
         defer allocator.free(key_with_null);
 
diff --git a/lib/std/target.zig b/lib/std/target.zig
index 6781ff250c..b81563d327 100644
--- a/lib/std/target.zig
+++ b/lib/std/target.zig
@@ -1,6 +1,9 @@
 const std = @import("std.zig");
 const builtin = std.builtin;
 
+/// TODO Nearly all the functions in this namespace would be
+/// better off if https://github.com/ziglang/zig/issues/425
+/// was solved.
 pub const Target = union(enum) {
     Native: void,
     Cross: Cross,
diff --git a/lib/std/thread.zig b/lib/std/thread.zig
index 278fcc827c..fbfb1afd1e 100644
--- a/lib/std/thread.zig
+++ b/lib/std/thread.zig
@@ -9,7 +9,7 @@ const assert = std.debug.assert;
 pub const Thread = struct {
     data: Data,
 
-    pub const use_pthreads = !windows.is_the_target and builtin.link_libc;
+    pub const use_pthreads = builtin.os != .windows and builtin.link_libc;
 
     /// Represents a kernel thread handle.
     /// May be an integer or a pointer depending on the platform.
@@ -309,7 +309,7 @@ pub const Thread = struct {
                 os.EINVAL => unreachable,
                 else => return os.unexpectedErrno(@intCast(usize, err)),
             }
-        } else if (os.linux.is_the_target) {
+        } else if (builtin.os == .linux) {
             var flags: u32 = os.CLONE_VM | os.CLONE_FS | os.CLONE_FILES | os.CLONE_SIGHAND |
                 os.CLONE_THREAD | os.CLONE_SYSVSEM | os.CLONE_PARENT_SETTID | os.CLONE_CHILD_CLEARTID |
                 os.CLONE_DETACHED;
@@ -342,18 +342,18 @@ pub const Thread = struct {
     };
 
     pub fn cpuCount() CpuCountError!usize {
-        if (os.linux.is_the_target) {
+        if (builtin.os == .linux) {
             const cpu_set = try os.sched_getaffinity(0);
             return usize(os.CPU_COUNT(cpu_set)); // TODO should not need this usize cast
         }
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             var system_info: windows.SYSTEM_INFO = undefined;
             windows.kernel32.GetSystemInfo(&system_info);
             return @intCast(usize, system_info.dwNumberOfProcessors);
         }
         var count: c_int = undefined;
         var count_len: usize = @sizeOf(c_int);
-        const name = if (os.darwin.is_the_target) c"hw.logicalcpu" else c"hw.ncpu";
+        const name = if (comptime std.Target.current.isDarwin()) c"hw.logicalcpu" else c"hw.ncpu";
         os.sysctlbynameC(name, &count, &count_len, null, 0) catch |err| switch (err) {
             error.NameTooLong => unreachable,
             else => |e| return e,
diff --git a/lib/std/time.zig b/lib/std/time.zig
index caf6c31b31..04dbb908e2 100644
--- a/lib/std/time.zig
+++ b/lib/std/time.zig
@@ -9,7 +9,7 @@ pub const epoch = @import("time/epoch.zig");
 
 /// Spurious wakeups are possible and no precision of timing is guaranteed.
 pub fn sleep(nanoseconds: u64) void {
-    if (os.windows.is_the_target) {
+    if (builtin.os == .windows) {
         const ns_per_ms = ns_per_s / ms_per_s;
         const big_ms_from_ns = nanoseconds / ns_per_ms;
         const ms = math.cast(os.windows.DWORD, big_ms_from_ns) catch math.maxInt(os.windows.DWORD);
@@ -30,7 +30,7 @@ pub fn timestamp() u64 {
 /// Get the posix timestamp, UTC, in milliseconds
 /// TODO audit this function. is it possible to return an error?
 pub fn milliTimestamp() u64 {
-    if (os.windows.is_the_target) {
+    if (builtin.os == .windows) {
         //FileTime has a granularity of 100 nanoseconds
         //  and uses the NTFS/Windows epoch
         var ft: os.windows.FILETIME = undefined;
@@ -41,7 +41,7 @@ pub fn milliTimestamp() u64 {
         const ft64 = (u64(ft.dwHighDateTime) << 32) | ft.dwLowDateTime;
         return @divFloor(ft64, hns_per_ms) - -epoch_adj;
     }
-    if (os.wasi.is_the_target and !builtin.link_libc) {
+    if (builtin.os == .wasi and !builtin.link_libc) {
         var ns: os.wasi.timestamp_t = undefined;
 
         // TODO: Verify that precision is ignored
@@ -51,7 +51,7 @@ pub fn milliTimestamp() u64 {
         const ns_per_ms = 1000;
         return @divFloor(ns, ns_per_ms);
     }
-    if (os.darwin.is_the_target) {
+    if (comptime std.Target.current.isDarwin()) {
         var tv: os.darwin.timeval = undefined;
         var err = os.darwin.gettimeofday(&tv, null);
         assert(err == 0);
@@ -126,11 +126,11 @@ pub const Timer = struct {
     pub fn start() Error!Timer {
         var self: Timer = undefined;
 
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             self.frequency = os.windows.QueryPerformanceFrequency();
             self.resolution = @divFloor(ns_per_s, self.frequency);
             self.start_time = os.windows.QueryPerformanceCounter();
-        } else if (os.darwin.is_the_target) {
+        } else if (comptime std.Target.current.isDarwin()) {
             os.darwin.mach_timebase_info(&self.frequency);
             self.resolution = @divFloor(self.frequency.numer, self.frequency.denom);
             self.start_time = os.darwin.mach_absolute_time();
@@ -154,10 +154,10 @@ pub const Timer = struct {
     /// Reads the timer value since start or the last reset in nanoseconds
     pub fn read(self: *Timer) u64 {
         var clock = clockNative() - self.start_time;
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             return @divFloor(clock * ns_per_s, self.frequency);
         }
-        if (os.darwin.is_the_target) {
+        if (comptime std.Target.current.isDarwin()) {
             return @divFloor(clock * self.frequency.numer, self.frequency.denom);
         }
         return clock;
@@ -177,10 +177,10 @@ pub const Timer = struct {
     }
 
     fn clockNative() u64 {
-        if (os.windows.is_the_target) {
+        if (builtin.os == .windows) {
             return os.windows.QueryPerformanceCounter();
         }
-        if (os.darwin.is_the_target) {
+        if (comptime std.Target.current.isDarwin()) {
             return os.darwin.mach_absolute_time();
         }
         var ts: os.timespec = undefined;