diff --git a/libcxx/include/__threading_support b/libcxx/include/__threading_support
index 8b0b2eda9b07..aa947139a4e9 100644
--- a/libcxx/include/__threading_support
+++ b/libcxx/include/__threading_support
@@ -589,14 +589,12 @@ void __libcpp_thread_yield()
 
 void __libcpp_thread_sleep_for(const chrono::nanoseconds& __ns)
 {
-  using namespace _VSTD::chrono;
-
+  using namespace chrono;
   // round-up to the nearest milisecond
   milliseconds __ms =
       duration_cast<milliseconds>(__ns + chrono::nanoseconds(999999));
-  auto start = system_clock::now();
-  while (::SleepEx((__ms - (system_clock::now() - start)).count(),
-                   TRUE) == WAIT_IO_COMPLETION);
+  // FIXME(compnerd) this should be an alertable sleep (WFSO or SleepEx)
+  Sleep(__ms.count());
 }
 
 // Thread Local Storage