diff --git a/compiler-rt/test/tsan/Darwin/libcxx-shared-ptr-stress.mm b/compiler-rt/test/tsan/Darwin/libcxx-shared-ptr-stress.mm
--- a/compiler-rt/test/tsan/Darwin/libcxx-shared-ptr-stress.mm
+++ b/compiler-rt/test/tsan/Darwin/libcxx-shared-ptr-stress.mm
@@ -3,33 +3,35 @@
 
 #import <Foundation/Foundation.h>
 
-#import <assert.h>
+#import <atomic>
+#import <cassert>
+#import <cstdio>
 #import <memory>
-#import <stdatomic.h>
 
-_Atomic(long) shared_call_counter = 0;
-_Atomic(long) weak_call_counter = 0;
-_Atomic(long) destructor_counter = 0;
-_Atomic(long) weak_destroyed_counter = 0;
+std::atomic<long> shared_call_counter(0);
+std::atomic<long> weak_call_counter(0);
+std::atomic<long> destructor_counter(0);
+std::atomic<long> weak_destroyed_counter(0);
 
 struct MyStruct {
-  _Atomic(long) self_counter = 0;
+  std::atomic<long> self_counter;
+  MyStruct() : self_counter(0) { }
   virtual void shared_call() {
-    atomic_fetch_add_explicit(&self_counter, 1, memory_order_relaxed);
-    atomic_fetch_add_explicit(&shared_call_counter, 1, memory_order_relaxed);
+    std::atomic_fetch_add_explicit(&self_counter, 1, std::memory_order_relaxed);
+    std::atomic_fetch_add_explicit(&shared_call_counter, 1, std::memory_order_relaxed);
   }
   virtual void weak_call() {
-    atomic_fetch_add_explicit(&weak_call_counter, 1, memory_order_relaxed);
+    std::atomic_fetch_add_explicit(&weak_call_counter, 1, std::memory_order_relaxed);
   }
   virtual ~MyStruct() {
     long n = self_counter;
     assert(n == 1000);
-    atomic_fetch_add_explicit(&destructor_counter, 1, memory_order_relaxed);
+    std::atomic_fetch_add_explicit(&destructor_counter, 1, std::memory_order_relaxed);
   }
 };
 
 int main(int argc, const char *argv[]) {
-  fprintf(stderr, "Hello world.\n");
+  std::fprintf(stderr, "Hello world.\n");
 
   dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
 
@@ -51,7 +53,7 @@
         if (weak_copy) {
           weak_copy->weak_call();
         } else {
-          atomic_fetch_add_explicit(&weak_destroyed_counter, 1, memory_order_relaxed);
+          std::atomic_fetch_add_explicit(&weak_destroyed_counter, 1, std::memory_order_relaxed);
           break;
         }
       }
@@ -60,12 +62,12 @@
 
   dispatch_group_wait(g, DISPATCH_TIME_FOREVER);
 
-  fprintf(stderr, "shared_call_counter = %ld\n", shared_call_counter);
-  fprintf(stderr, "weak_call_counter = %ld\n", weak_call_counter);
-  fprintf(stderr, "destructor_counter = %ld\n", destructor_counter);
-  fprintf(stderr, "weak_destroyed_counter = %ld\n", weak_destroyed_counter);
+  std::fprintf(stderr, "shared_call_counter = %ld\n", shared_call_counter.load());
+  std::fprintf(stderr, "weak_call_counter = %ld\n", weak_call_counter.load());
+  std::fprintf(stderr, "destructor_counter = %ld\n", destructor_counter.load());
+  std::fprintf(stderr, "weak_destroyed_counter = %ld\n", weak_destroyed_counter.load());
 
-  fprintf(stderr, "Done.\n");
+  std::fprintf(stderr, "Done.\n");
 }
 
 // CHECK: Hello world.
diff --git a/compiler-rt/test/tsan/libdispatch/groups-destructor.cpp b/compiler-rt/test/tsan/libdispatch/groups-destructor.cpp
--- a/compiler-rt/test/tsan/libdispatch/groups-destructor.cpp
+++ b/compiler-rt/test/tsan/libdispatch/groups-destructor.cpp
@@ -3,21 +3,21 @@
 
 #include <dispatch/dispatch.h>
 
-#include <memory>
-#include <stdatomic.h>
+#include <atomic>
 #include <cstdio>
+#include <memory>
 
-_Atomic(long) destructor_counter = 0;
+std::atomic<long> destructor_counter(0);
 
 struct MyStruct {
   virtual ~MyStruct() {
     usleep(10000);
-    atomic_fetch_add_explicit(&destructor_counter, 1, memory_order_relaxed);
+    std::atomic_fetch_add_explicit(&destructor_counter, 1, std::memory_order_relaxed);
   }
 };
 
 int main(int argc, const char *argv[]) {
-  fprintf(stderr, "Hello world.\n");
+  std::fprintf(stderr, "Hello world.\n");
 
   dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
   dispatch_group_t g = dispatch_group_create();
@@ -33,10 +33,10 @@
   dispatch_group_wait(g, DISPATCH_TIME_FOREVER);
 
   if (destructor_counter != 100) {
-    abort();
+    std::abort();
   }
 
-  fprintf(stderr, "Done.\n");
+  std::fprintf(stderr, "Done.\n");
 }
 
 // CHECK: Hello world.