diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/thread.lock.shared.cons/mutex_try_to_lock.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/thread.lock.shared.cons/mutex_try_to_lock.pass.cpp
--- a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/thread.lock.shared.cons/mutex_try_to_lock.pass.cpp
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/thread.lock.shared.cons/mutex_try_to_lock.pass.cpp
@@ -36,6 +36,16 @@
 typedef std::chrono::milliseconds ms;
 typedef std::chrono::nanoseconds ns;
 
+
+// Thread sanitizer causes more overhead and will sometimes cause this test
+// to fail. To prevent this we give Thread sanitizer more time to complete the
+// test.
+#if !defined(TEST_IS_EXECUTED_IN_A_SLOW_ENVIRONMENT)
+ms Tolerance = ms(200);
+#else
+ms Tolerance = ms(200 * 5);
+#endif
+
 void f()
 {
     time_point t0 = Clock::now();
@@ -56,10 +66,11 @@
         std::shared_lock<std::shared_timed_mutex> lk(m, std::try_to_lock);
         if (lk.owns_lock())
             break;
+        std::this_thread::yield();
     }
     time_point t1 = Clock::now();
     ns d = t1 - t0 - ms(250);
-    assert(d < ms(200));  // within 200ms
+    assert(d < Tolerance);  // within tolerance
 }
 
 int main(int, char**)
diff --git a/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.shared_mutex.requirements/thread.shared_mutex.class/try_lock_shared.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.shared_mutex.requirements/thread.shared_mutex.class/try_lock_shared.pass.cpp
--- a/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.shared_mutex.requirements/thread.shared_mutex.class/try_lock_shared.pass.cpp
+++ b/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.shared_mutex.requirements/thread.shared_mutex.class/try_lock_shared.pass.cpp
@@ -37,6 +37,16 @@
 typedef std::chrono::milliseconds ms;
 typedef std::chrono::nanoseconds ns;
 
+
+// Thread sanitizer causes more overhead and will sometimes cause this test
+// to fail. To prevent this we give Thread sanitizer more time to complete the
+// test.
+#if !defined(TEST_IS_EXECUTED_IN_A_SLOW_ENVIRONMENT)
+ms Tolerance = ms(200);
+#else
+ms Tolerance = ms(200 * 5);
+#endif
+
 void f()
 {
     time_point t0 = Clock::now();
@@ -44,11 +54,11 @@
     assert(!m.try_lock_shared());
     assert(!m.try_lock_shared());
     while(!m.try_lock_shared())
-        ;
+        std::this_thread::yield();
     time_point t1 = Clock::now();
     m.unlock_shared();
     ns d = t1 - t0 - ms(250);
-    assert(d < ms(200));  // within 200ms
+    assert(d < Tolerance);  // within tolerance
 }
 
 
diff --git a/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared.pass.cpp
--- a/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared.pass.cpp
+++ b/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared.pass.cpp
@@ -54,7 +54,7 @@
     assert(!m.try_lock_shared());
     assert(!m.try_lock_shared());
     while(!m.try_lock_shared())
-        ;
+        std::this_thread::yield();
     time_point t1 = Clock::now();
     m.unlock_shared();
     ns d = t1 - t0 - ms(250);