diff --git a/libcxx/include/__threading_support b/libcxx/include/__threading_support
--- a/libcxx/include/__threading_support
+++ b/libcxx/include/__threading_support
@@ -64,7 +64,11 @@
 #if defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
 // Mutex
 typedef pthread_mutex_t __libcpp_mutex_t;
+#if defined(__USE_GNU) && defined(PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP)
+#define _LIBCPP_MUTEX_INITIALIZER PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
+#else
 #define _LIBCPP_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
+#endif
 
 typedef pthread_mutex_t __libcpp_recursive_mutex_t;