Index: libcxx/include/__threading_support
===================================================================
--- libcxx/include/__threading_support
+++ libcxx/include/__threading_support
@@ -395,6 +395,19 @@
 
 #endif // !_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL || _LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL
 
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // !_LIBCPP_HAS_NO_THREADS and !_LIBCPP_HAS_THREAD_API_EXTERNAL
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 class _LIBCPP_TYPE_VIS thread;
 class _LIBCPP_TYPE_VIS __thread_id;