Index: test/tsan/barrier.cc
===================================================================
--- test/tsan/barrier.cc
+++ test/tsan/barrier.cc
@@ -2,10 +2,7 @@
 // CHECK-NOT: ThreadSanitizer: data race
 // CHECK: DONE
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <pthread.h>
-#include <unistd.h>
+#include "test.h"
 
 const int kSize = 4;
 volatile int kIter = 10;  // prevent unwinding
Index: test/tsan/bench.h
===================================================================
--- test/tsan/bench.h
+++ test/tsan/bench.h
@@ -5,6 +5,8 @@
 #include <stdio.h>
 #include <time.h>
 
+#include "test.h"
+
 int bench_nthread;
 int bench_niter;
 int grow_clock_var;
@@ -31,14 +33,9 @@
   pthread_barrier_destroy(&glow_clock_barrier);
   __atomic_load_n(&grow_clock_var, __ATOMIC_ACQUIRE);
 
-  timespec tp0;
-  clock_gettime(CLOCK_MONOTONIC, &tp0);
+  BENCH_STOPWATCH_START();
   bench();
-  timespec tp1;
-  clock_gettime(CLOCK_MONOTONIC, &tp1);
-  unsigned long long t =
-      (tp1.tv_sec * 1000000000ULL + tp1.tv_nsec) -
-      (tp0.tv_sec * 1000000000ULL + tp0.tv_nsec);
+  BENCH_STOPWATCH_STOP();
   fprintf(stderr, "%llu ns/iter\n", t / bench_niter);
   fprintf(stderr, "DONE\n");
 }
Index: test/tsan/race_on_barrier2.c
===================================================================
--- test/tsan/race_on_barrier2.c
+++ test/tsan/race_on_barrier2.c
@@ -1,8 +1,5 @@
 // RUN: %clang_tsan -O1 %s -o %t && %deflake %run %t | FileCheck %s
-#include <pthread.h>
-#include <stdio.h>
-#include <stddef.h>
-#include <unistd.h>
+#include "test.h"
 
 pthread_barrier_t B;
 int Global;
Index: test/tsan/test.h
===================================================================
--- test/tsan/test.h
+++ test/tsan/test.h
@@ -1,3 +1,4 @@
+#include <assert.h>
 #include <pthread.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -6,6 +7,10 @@
 #include <stddef.h>
 #include <sched.h>
 
+#ifdef __APPLE__
+#include <mach/mach_time.h>
+#endif
+
 // TSan-invisible barrier.
 // Tests use it to establish necessary execution order in a way that does not
 // interfere with tsan (does not establish synchronization between threads).
@@ -60,3 +65,73 @@
   fprintf(stderr, format, (unsigned long) address);
 #endif
 }
+
+#ifdef __APPLE__
+
+// Darwin doesn't have pthread_barrier_* APIs, let's re-implement them with
+// mutexes and condition variables.
+typedef int pthread_barrierattr_t;
+typedef struct {
+  pthread_mutex_t mutex;
+  pthread_cond_t cond;
+  int current_count;
+  int max_count;
+} pthread_barrier_t;
+#define PTHREAD_BARRIER_SERIAL_THREAD 1
+
+int pthread_barrier_init(pthread_barrier_t *barrier,
+                         const pthread_barrierattr_t *attr, unsigned count) {
+  assert(count > 0);
+  assert(pthread_mutex_init(&barrier->mutex, 0) == 0);
+  assert(pthread_cond_init(&barrier->cond, 0) == 0);
+  barrier->max_count = count;
+  barrier->current_count = 0;
+  return 0;
+}
+
+int pthread_barrier_wait(pthread_barrier_t *barrier) {
+  pthread_mutex_lock(&barrier->mutex);
+  barrier->current_count += 1;
+  if (barrier->current_count >= barrier->max_count) {
+    barrier->current_count = 0;
+    pthread_cond_broadcast(&barrier->cond);
+    pthread_mutex_unlock(&barrier->mutex);
+    return PTHREAD_BARRIER_SERIAL_THREAD;
+  } else {
+    pthread_cond_wait(&barrier->cond, &barrier->mutex);
+    pthread_mutex_unlock(&barrier->mutex);
+    return 0;
+  }
+}
+
+int pthread_barrier_destroy(pthread_barrier_t *barrier) {
+  pthread_cond_destroy(&barrier->cond);
+  pthread_mutex_destroy(&barrier->mutex);
+  return 0;
+}
+
+unsigned long long darwin_uptime() {
+  static mach_timebase_info_data_t timebase_info;
+  if (timebase_info.denom == 0) mach_timebase_info(&timebase_info);
+  return (mach_absolute_time() * timebase_info.numer) / timebase_info.denom;
+}
+
+#define BENCH_STOPWATCH_START() \
+  unsigned long long tp0 = darwin_uptime()
+#define BENCH_STOPWATCH_STOP() \
+  unsigned long long tp1 = darwin_uptime(); \
+  unsigned long long t = tp1 - tp0
+
+#else  // __APPLE__
+
+#define BENCH_STOPWATCH_START() \
+  timespec tp0; \
+  clock_gettime(CLOCK_MONOTONIC, &tp0)
+#define BENCH_STOPWATCH_STOP() \
+  timespec tp1; \
+  clock_gettime(CLOCK_MONOTONIC, &tp1); \
+  unsigned long long t = \
+      (tp1.tv_sec * 1000000000ULL + tp1.tv_nsec) - \
+      (tp0.tv_sec * 1000000000ULL + tp0.tv_nsec)
+
+#endif  // __APPLE__