Index: libcxx/include/atomic
===================================================================
--- libcxx/include/atomic
+++ libcxx/include/atomic
@@ -552,7 +552,9 @@
 #ifdef _LIBCPP_HAS_NO_THREADS
 #error <atomic> is not supported on this single threaded system
 #endif
-#if !defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_GCC_ATOMIC_IMP)
+#if !defined(_LIBCPP_HAS_C_ATOMIC_IMP) && \
+    !defined(_LIBCPP_HAS_GCC_ATOMIC_IMP) && \
+    !defined(_LIBCPP_HAS_EXTERNAL_ATOMIC_IMP)
 #error <atomic> is not implemented
 #endif
 #ifdef kill_dependency
@@ -577,6 +579,15 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#ifndef _LIBCPP_ATOMIC_FLAG_TYPE
+#define _LIBCPP_ATOMIC_FLAG_TYPE bool
+#endif
+
+#ifndef _LIBCPP_ATOMIC_SCOPE_DEFAULT
+struct __cxx_atomic_scope { };
+#define _LIBCPP_ATOMIC_SCOPE_DEFAULT __cxx_atomic_scope
+#endif
+
 typedef enum memory_order
 {
     memory_order_relaxed, memory_order_consume, memory_order_acquire,
@@ -584,9 +595,9 @@
 } memory_order;
 
 #if defined(_LIBCPP_HAS_GCC_ATOMIC_IMP)
-namespace __gcc_atomic {
+
 template <typename _Tp>
-struct __gcc_atomic_t {
+struct __cxx_atomic_type {
 
 #if _GNUC_VER >= 501
     static_assert(is_trivially_copyable<_Tp>::value,
@@ -595,15 +606,17 @@
 
   _LIBCPP_INLINE_VISIBILITY
 #ifndef _LIBCPP_CXX03_LANG
-    __gcc_atomic_t() _NOEXCEPT = default;
+    __cxx_atomic_type() _NOEXCEPT = default;
 #else
-    __gcc_atomic_t() _NOEXCEPT : __a_value() {}
+    __cxx_atomic_type() _NOEXCEPT : __a_value() {}
 #endif // _LIBCPP_CXX03_LANG
-  _LIBCPP_CONSTEXPR explicit __gcc_atomic_t(_Tp value) _NOEXCEPT
+  _LIBCPP_CONSTEXPR explicit __cxx_atomic_type(_Tp value) _NOEXCEPT
     : __a_value(value) {}
   _Tp __a_value;
 };
-#define _Atomic(x) __gcc_atomic::__gcc_atomic_t<x>
+
+template<typename _Tp, typename _Sco>
+using __cxx_atomic_base_impl = __cxx_atomic_type<_Tp>;
 
 template <typename _Tp> _Tp __create();
 
@@ -639,22 +652,20 @@
               __ATOMIC_CONSUME))));
 }
 
-} // namespace __gcc_atomic
-
 template <typename _Tp>
 static inline
 typename enable_if<
-    __gcc_atomic::__can_assign<volatile _Atomic(_Tp)*, _Tp>::value>::type
-__c11_atomic_init(volatile _Atomic(_Tp)* __a,  _Tp __val) {
+    __cxx_atomic_type::__can_assign<volatile __cxx_atomic_type<_Tp>*, _Tp>::value>::type
+__cxx_atomic_init(volatile __cxx_atomic_type<_Tp>* __a,  _Tp __val) {
   __a->__a_value = __val;
 }
 
 template <typename _Tp>
 static inline
 typename enable_if<
-    !__gcc_atomic::__can_assign<volatile _Atomic(_Tp)*, _Tp>::value &&
-     __gcc_atomic::__can_assign<         _Atomic(_Tp)*, _Tp>::value>::type
-__c11_atomic_init(volatile _Atomic(_Tp)* __a,  _Tp __val) {
+    !__cxx_atomic_type::__can_assign<volatile __cxx_atomic_type<_Tp>*, _Tp>::value &&
+     __cxx_atomic_type::__can_assign<         __cxx_atomic_type<_Tp>*, _Tp>::value>::type
+__cxx_atomic_init(volatile __cxx_atomic_type<_Tp>* __a,  _Tp __val) {
   // [atomics.types.generic]p1 guarantees _Tp is trivially copyable. Because
   // the default operator= in an object is not volatile, a byte-by-byte copy
   // is required.
@@ -667,105 +678,105 @@
 }
 
 template <typename _Tp>
-static inline void __c11_atomic_init(_Atomic(_Tp)* __a,  _Tp __val) {
+static inline void __cxx_atomic_init(__cxx_atomic_type<_Tp>* __a,  _Tp __val) {
   __a->__a_value = __val;
 }
 
-static inline void __c11_atomic_thread_fence(memory_order __order) {
-  __atomic_thread_fence(__gcc_atomic::__to_gcc_order(__order));
+static inline void __cxx_atomic_thread_fence(memory_order __order) {
+  __atomic_thread_fence(__to_gcc_order(__order));
 }
 
-static inline void __c11_atomic_signal_fence(memory_order __order) {
-  __atomic_signal_fence(__gcc_atomic::__to_gcc_order(__order));
+static inline void __cxx_atomic_signal_fence(memory_order __order) {
+  __atomic_signal_fence(__to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline void __c11_atomic_store(volatile _Atomic(_Tp)* __a,  _Tp __val,
+static inline void __cxx_atomic_store(volatile __cxx_atomic_type<_Tp>* __a,  _Tp __val,
                                       memory_order __order) {
-  return __atomic_store(&__a->__a_value, &__val,
-                        __gcc_atomic::__to_gcc_order(__order));
+  __atomic_store(&__a->__a_value, &__val,
+                 __to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline void __c11_atomic_store(_Atomic(_Tp)* __a,  _Tp __val,
+static inline void __cxx_atomic_store(__cxx_atomic_type<_Tp>* __a,  _Tp __val,
                                       memory_order __order) {
   __atomic_store(&__a->__a_value, &__val,
-                 __gcc_atomic::__to_gcc_order(__order));
+                 __to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_load(const volatile _Atomic(_Tp)* __a,
+static inline _Tp __cxx_atomic_load(const volatile __cxx_atomic_type<_Tp>* __a,
                                     memory_order __order) {
   _Tp __ret;
   __atomic_load(&__a->__a_value, &__ret,
-                __gcc_atomic::__to_gcc_order(__order));
+                __to_gcc_order(__order));
   return __ret;
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_load(const _Atomic(_Tp)* __a, memory_order __order) {
+static inline _Tp __cxx_atomic_load(const __cxx_atomic_type<_Tp>* __a, memory_order __order) {
   _Tp __ret;
   __atomic_load(&__a->__a_value, &__ret,
-                __gcc_atomic::__to_gcc_order(__order));
+                __to_gcc_order(__order));
   return __ret;
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_exchange(volatile _Atomic(_Tp)* __a,
+static inline _Tp __cxx_atomic_exchange(volatile __cxx_atomic_type<_Tp>* __a,
                                         _Tp __value, memory_order __order) {
   _Tp __ret;
   __atomic_exchange(&__a->__a_value, &__value, &__ret,
-                    __gcc_atomic::__to_gcc_order(__order));
+                    __to_gcc_order(__order));
   return __ret;
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_exchange(_Atomic(_Tp)* __a, _Tp __value,
+static inline _Tp __cxx_atomic_exchange(__cxx_atomic_type<_Tp>* __a, _Tp __value,
                                         memory_order __order) {
   _Tp __ret;
   __atomic_exchange(&__a->__a_value, &__value, &__ret,
-                    __gcc_atomic::__to_gcc_order(__order));
+                    __to_gcc_order(__order));
   return __ret;
 }
 
 template <typename _Tp>
-static inline bool __c11_atomic_compare_exchange_strong(
-    volatile _Atomic(_Tp)* __a, _Tp* __expected, _Tp __value,
+static inline bool __cxx_atomic_compare_exchange_strong(
+    volatile __cxx_atomic_type<_Tp>* __a, _Tp* __expected, _Tp __value,
     memory_order __success, memory_order __failure) {
   return __atomic_compare_exchange(&__a->__a_value, __expected, &__value,
                                    false,
-                                   __gcc_atomic::__to_gcc_order(__success),
-                                   __gcc_atomic::__to_gcc_failure_order(__failure));
+                                   __to_gcc_order(__success),
+                                   __to_gcc_failure_order(__failure));
 }
 
 template <typename _Tp>
-static inline bool __c11_atomic_compare_exchange_strong(
-    _Atomic(_Tp)* __a, _Tp* __expected, _Tp __value, memory_order __success,
+static inline bool __cxx_atomic_compare_exchange_strong(
+    __cxx_atomic_type<_Tp>* __a, _Tp* __expected, _Tp __value, memory_order __success,
     memory_order __failure) {
   return __atomic_compare_exchange(&__a->__a_value, __expected, &__value,
                                    false,
-                                   __gcc_atomic::__to_gcc_order(__success),
-                                   __gcc_atomic::__to_gcc_failure_order(__failure));
+                                   __to_gcc_order(__success),
+                                   __to_gcc_failure_order(__failure));
 }
 
 template <typename _Tp>
-static inline bool __c11_atomic_compare_exchange_weak(
-    volatile _Atomic(_Tp)* __a, _Tp* __expected, _Tp __value,
+static inline bool __cxx_atomic_compare_exchange_weak(
+    volatile __cxx_atomic_type<_Tp>* __a, _Tp* __expected, _Tp __value,
     memory_order __success, memory_order __failure) {
   return __atomic_compare_exchange(&__a->__a_value, __expected, &__value,
                                    true,
-                                   __gcc_atomic::__to_gcc_order(__success),
-                                   __gcc_atomic::__to_gcc_failure_order(__failure));
+                                   __to_gcc_order(__success),
+                                   __to_gcc_failure_order(__failure));
 }
 
 template <typename _Tp>
-static inline bool __c11_atomic_compare_exchange_weak(
-    _Atomic(_Tp)* __a, _Tp* __expected, _Tp __value, memory_order __success,
+static inline bool __cxx_atomic_compare_exchange_weak(
+    __cxx_atomic_type<_Tp>* __a, _Tp* __expected, _Tp __value, memory_order __success,
     memory_order __failure) {
   return __atomic_compare_exchange(&__a->__a_value, __expected, &__value,
                                    true,
-                                   __gcc_atomic::__to_gcc_order(__success),
-                                   __gcc_atomic::__to_gcc_failure_order(__failure));
+                                   __to_gcc_order(__success),
+                                   __to_gcc_failure_order(__failure));
 }
 
 template <typename _Tp>
@@ -782,74 +793,268 @@
 struct __skip_amt<_Tp[n]> { };
 
 template <typename _Tp, typename _Td>
-static inline _Tp __c11_atomic_fetch_add(volatile _Atomic(_Tp)* __a,
-                                         _Td __delta, memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_add(volatile __cxx_atomic_type<_Tp>* __a,
+                           _Td __delta, memory_order __order) {
   return __atomic_fetch_add(&__a->__a_value, __delta * __skip_amt<_Tp>::value,
-                            __gcc_atomic::__to_gcc_order(__order));
+                            __to_gcc_order(__order));
 }
 
 template <typename _Tp, typename _Td>
-static inline _Tp __c11_atomic_fetch_add(_Atomic(_Tp)* __a, _Td __delta,
-                                         memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_add(__cxx_atomic_type<_Tp>* __a, _Td __delta,
+                           memory_order __order) {
   return __atomic_fetch_add(&__a->__a_value, __delta * __skip_amt<_Tp>::value,
-                            __gcc_atomic::__to_gcc_order(__order));
+                            __to_gcc_order(__order));
 }
 
 template <typename _Tp, typename _Td>
-static inline _Tp __c11_atomic_fetch_sub(volatile _Atomic(_Tp)* __a,
-                                         _Td __delta, memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_sub(volatile __cxx_atomic_type<_Tp>* __a,
+                           _Td __delta, memory_order __order) {
   return __atomic_fetch_sub(&__a->__a_value, __delta * __skip_amt<_Tp>::value,
-                            __gcc_atomic::__to_gcc_order(__order));
+                            __to_gcc_order(__order));
 }
 
 template <typename _Tp, typename _Td>
-static inline _Tp __c11_atomic_fetch_sub(_Atomic(_Tp)* __a, _Td __delta,
-                                         memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_sub(__cxx_atomic_type<_Tp>* __a, _Td __delta,
+                           memory_order __order) {
   return __atomic_fetch_sub(&__a->__a_value, __delta * __skip_amt<_Tp>::value,
-                            __gcc_atomic::__to_gcc_order(__order));
+                            __to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_fetch_and(volatile _Atomic(_Tp)* __a,
-                                         _Tp __pattern, memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_and(volatile __cxx_atomic_type<_Tp>* __a,
+                           _Tp __pattern, memory_order __order) {
   return __atomic_fetch_and(&__a->__a_value, __pattern,
-                            __gcc_atomic::__to_gcc_order(__order));
+                            __to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_fetch_and(_Atomic(_Tp)* __a,
-                                         _Tp __pattern, memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_and(__cxx_atomic_type<_Tp>* __a,
+                           _Tp __pattern, memory_order __order) {
   return __atomic_fetch_and(&__a->__a_value, __pattern,
-                            __gcc_atomic::__to_gcc_order(__order));
+                            __to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_fetch_or(volatile _Atomic(_Tp)* __a,
-                                        _Tp __pattern, memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_or(volatile __cxx_atomic_type<_Tp>* __a,
+                          _Tp __pattern, memory_order __order) {
   return __atomic_fetch_or(&__a->__a_value, __pattern,
-                           __gcc_atomic::__to_gcc_order(__order));
+                           __to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_fetch_or(_Atomic(_Tp)* __a, _Tp __pattern,
-                                        memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_or(__cxx_atomic_type<_Tp>* __a, _Tp __pattern,
+                          memory_order __order) {
   return __atomic_fetch_or(&__a->__a_value, __pattern,
-                           __gcc_atomic::__to_gcc_order(__order));
+                           __to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_fetch_xor(volatile _Atomic(_Tp)* __a,
-                                         _Tp __pattern, memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_xor(volatile __cxx_atomic_type<_Tp>* __a,
+                           _Tp __pattern, memory_order __order) {
   return __atomic_fetch_xor(&__a->__a_value, __pattern,
-                            __gcc_atomic::__to_gcc_order(__order));
+                            __to_gcc_order(__order));
 }
 
 template <typename _Tp>
-static inline _Tp __c11_atomic_fetch_xor(_Atomic(_Tp)* __a, _Tp __pattern,
-                                         memory_order __order) {
+static inline _Tp __cxx_atomic_fetch_xor(__cxx_atomic_type<_Tp>* __a, _Tp __pattern,
+                           memory_order __order) {
   return __atomic_fetch_xor(&__a->__a_value, __pattern,
-                            __gcc_atomic::__to_gcc_order(__order));
+                            __to_gcc_order(__order));
+}
+
+#define __cxx_atomic_is_lock_free(__s) __atomic_is_lock_free(__s, 0)
+
+#elif defined(_LIBCPP_HAS_C_ATOMIC_IMP)
+
+template <typename _Tp>
+struct __cxx_atomic_type {
+
+#if _GNUC_VER >= 501
+    static_assert(is_trivially_copyable<_Tp>::value,
+      "std::atomic<Tp> requires that 'Tp' be a trivially copyable type");
+#endif
+
+  _LIBCPP_INLINE_VISIBILITY
+#ifndef _LIBCPP_CXX03_LANG
+    __cxx_atomic_type() _NOEXCEPT = default;
+#else
+    __cxx_atomic_type() _NOEXCEPT : __a_value() {}
+#endif // _LIBCPP_CXX03_LANG
+  _LIBCPP_CONSTEXPR explicit __cxx_atomic_type(_Tp value) _NOEXCEPT
+    : __a_value(value) {}
+  _Atomic(_Tp) __a_value;
+};
+
+template<typename _Tp, typename _Sco>
+using __cxx_atomic_base_impl = __cxx_atomic_type<_Tp>;
+
+#define __cxx_atomic_is_lock_free(__s) __c11_atomic_is_lock_free(__s)
+
+static _LIBCPP_INLINE_VISIBILITY inline 
+void __cxx_atomic_thread_fence(int __order) {
+    __c11_atomic_thread_fence(__order); 
+}
+
+static _LIBCPP_INLINE_VISIBILITY inline 
+void __cxx_atomic_signal_fence(int __order) {
+    __c11_atomic_signal_fence(__order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+void __cxx_atomic_init(__cxx_atomic_type<_Tp> volatile* __a, _Tp __val) { 
+    __c11_atomic_init(&__a->__a_value, __val); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+void __cxx_atomic_init(__cxx_atomic_type<_Tp> * __a, _Tp __val) { 
+    __c11_atomic_init(&__a->__a_value, __val); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+void __cxx_atomic_store(__cxx_atomic_type<_Tp> volatile* __a, _Tp __val, int __order) {
+    __c11_atomic_store(&__a->__a_value, __val, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+void __cxx_atomic_store(__cxx_atomic_type<_Tp> * __a, _Tp __val, int __order) {
+    __c11_atomic_store(&__a->__a_value, __val, __order); 
+}
+
+template<class _Tp>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_load(__cxx_atomic_type<_Tp> const volatile* __a, int __order) {
+    using __ptr_type = typename remove_const<decltype(__a->__a_value)>::type*;
+    return __c11_atomic_load(const_cast<__ptr_type>(&__a->__a_value), __order); 
+}
+template<class _Tp>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_load(__cxx_atomic_type<_Tp> const* __a, int __order) {
+    using __ptr_type = typename remove_const<decltype(__a->__a_value)>::type*;
+    return __c11_atomic_load(const_cast<__ptr_type>(&__a->__a_value), __order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_exchange(__cxx_atomic_type<_Tp> volatile* __a, _Tp __value, int __order) {
+    return __c11_atomic_exchange(&__a->__a_value, __value, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_exchange(__cxx_atomic_type<_Tp> * __a, _Tp __value, int __order) {
+    return __c11_atomic_exchange(&__a->__a_value, __value, __order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+bool __cxx_atomic_compare_exchange_strong(__cxx_atomic_type<_Tp> volatile* __a, _Tp* __expected, _Tp __value, int __success, int __failure) {
+    return __c11_atomic_compare_exchange_strong(&__a->__a_value, __expected, __value, __success, __failure); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+bool __cxx_atomic_compare_exchange_strong(__cxx_atomic_type<_Tp> * __a, _Tp* __expected, _Tp __value, int __success, int __failure) {
+    return __c11_atomic_compare_exchange_strong(&__a->__a_value, __expected, __value, __success, __failure); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+bool __cxx_atomic_compare_exchange_weak(__cxx_atomic_type<_Tp> volatile* __a, _Tp* __expected, _Tp __value, int __success, int __failure) {
+    return __c11_atomic_compare_exchange_weak(&__a->__a_value, __expected, __value, __success, __failure); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+bool __cxx_atomic_compare_exchange_weak(__cxx_atomic_type<_Tp> * __a, _Tp* __expected, _Tp __value, int __success, int __failure) {
+    return __c11_atomic_compare_exchange_weak(&__a->__a_value, __expected, __value,  __success, __failure); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_add(__cxx_atomic_type<_Tp> volatile* __a, _Tp __delta, int __order) {
+    return __c11_atomic_fetch_add(&__a->__a_value, __delta, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_add(__cxx_atomic_type<_Tp> * __a, _Tp __delta, int __order) {
+    return __c11_atomic_fetch_add(&__a->__a_value, __delta, __order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp* __cxx_atomic_fetch_add(__cxx_atomic_type<_Tp*> volatile* __a, ptrdiff_t __delta, int __order) {
+    return __c11_atomic_fetch_add(&__a->__a_value, __delta, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp* __cxx_atomic_fetch_add(__cxx_atomic_type<_Tp*> * __a, ptrdiff_t __delta, int __order) {
+    return __c11_atomic_fetch_add(&__a->__a_value, __delta, __order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_sub(__cxx_atomic_type<_Tp> volatile* __a, _Tp __delta, int __order) {
+    return __c11_atomic_fetch_sub(&__a->__a_value, __delta, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_sub(__cxx_atomic_type<_Tp> * __a, _Tp __delta, int __order) {
+    return __c11_atomic_fetch_sub(&__a->__a_value, __delta, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp* __cxx_atomic_fetch_sub(__cxx_atomic_type<_Tp*> volatile* __a, ptrdiff_t __delta, int __order) {
+    return __c11_atomic_fetch_sub(&__a->__a_value, __delta, __order); 
 }
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp* __cxx_atomic_fetch_sub(__cxx_atomic_type<_Tp*> * __a, ptrdiff_t __delta, int __order) {
+    return __c11_atomic_fetch_sub(&__a->__a_value, __delta, __order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_and(__cxx_atomic_type<_Tp> volatile* __a, _Tp __pattern, int __order) {
+    return __c11_atomic_fetch_and(&__a->__a_value, __pattern, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_and(__cxx_atomic_type<_Tp> * __a, _Tp __pattern, int __order) {
+    return __c11_atomic_fetch_and(&__a->__a_value, __pattern, __order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_or(__cxx_atomic_type<_Tp> volatile* __a, _Tp __pattern, int __order) {
+    return __c11_atomic_fetch_or(&__a->__a_value, __pattern, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_or(__cxx_atomic_type<_Tp> * __a, _Tp __pattern, int __order) {
+    return __c11_atomic_fetch_or(&__a->__a_value, __pattern, __order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_xor(__cxx_atomic_type<_Tp> volatile* __a, _Tp __pattern, int __order) {
+    return __c11_atomic_fetch_xor(&__a->__a_value, __pattern, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_xor(__cxx_atomic_type<_Tp> * __a, _Tp __pattern, int __order) {
+    return __c11_atomic_fetch_xor(&__a->__a_value, __pattern, __order); 
+}
+
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp* __cxx_atomic_fetch_add(_Atomic(_Tp*) volatile* __a, ptrdiff_t __delta, int __order) {
+    return __c11_atomic_fetch_add(&__a->__a_value, __delta, __order); 
+}
+template<class _Tp> 
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp* __cxx_atomic_fetch_add(_Atomic(_Tp*) * __a, ptrdiff_t __delta, int __order) {
+    return __c11_atomic_fetch_add(&__a->__a_value, __delta, __order); 
+}
+
 #endif // _LIBCPP_HAS_GCC_ATOMIC_IMP
 
 template <class _Tp>
@@ -871,7 +1076,7 @@
 # define ATOMIC_LONG_LOCK_FREE      __CLANG_ATOMIC_LONG_LOCK_FREE
 # define ATOMIC_LLONG_LOCK_FREE     __CLANG_ATOMIC_LLONG_LOCK_FREE
 # define ATOMIC_POINTER_LOCK_FREE   __CLANG_ATOMIC_POINTER_LOCK_FREE
-#else
+#elif defined(__cxx_atomic_type_BOOL_LOCK_FREE)
 # define ATOMIC_BOOL_LOCK_FREE      __GCC_ATOMIC_BOOL_LOCK_FREE
 # define ATOMIC_CHAR_LOCK_FREE      __GCC_ATOMIC_CHAR_LOCK_FREE
 # define ATOMIC_CHAR16_T_LOCK_FREE  __GCC_ATOMIC_CHAR16_T_LOCK_FREE
@@ -884,12 +1089,173 @@
 # define ATOMIC_POINTER_LOCK_FREE   __GCC_ATOMIC_POINTER_LOCK_FREE
 #endif
 
+#if defined(_LIBCPP_FREESTANDING) && defined(__cpp_lib_atomic_is_always_lock_free)
+
+template<typename _Tp, typename _Sco>
+struct __cxx_atomic_lock_impl {
+
+#if _GNUC_VER >= 501
+    static_assert(is_trivially_copyable<_Tp>::value,
+      "std::atomic<Tp> requires that 'Tp' be a trivially copyable type");
+#endif
+
+  _LIBCPP_INLINE_VISIBILITY
+    __cxx_atomic_lock_impl() _NOEXCEPT 
+    : __a_value(), __a_lock(0) {}
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_CONSTEXPR explicit __cxx_atomic_lock_impl(_Tp value) _NOEXCEPT
+    : __a_value(value), __a_lock(0) {}
+
+  _Tp __a_value;
+  mutable __cxx_atomic_base_impl<_LIBCPP_ATOMIC_FLAG_TYPE, _Sco> __a_lock;
+
+    template<typename _Function>
+    _LIBCPP_INLINE_VISIBILITY inline void reader_section(_Function && __f) const volatile {
+        while(1 == __cxx_atomic_exchange(&__a_lock, _LIBCPP_ATOMIC_FLAG_TYPE(true), __ATOMIC_ACQUIRE));
+        __f(__a_value);
+        __cxx_atomic_store(&__a_lock, _LIBCPP_ATOMIC_FLAG_TYPE(false), __ATOMIC_RELEASE);
+    }
+    template<typename _Function>
+    _LIBCPP_INLINE_VISIBILITY inline void writer_section(_Function && __f) volatile {
+        while(1 == __cxx_atomic_exchange(&__a_lock, _LIBCPP_ATOMIC_FLAG_TYPE(true), __ATOMIC_ACQUIRE));
+        __f(__a_value);
+        __cxx_atomic_store(&__a_lock, _LIBCPP_ATOMIC_FLAG_TYPE(false), __ATOMIC_RELEASE);
+    }
+};
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+void __cxx_atomic_init(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a,  _Tp __val) {
+  __a->__a_value = __val;
+}
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+void __cxx_atomic_store(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a,  _Tp __val, int) {
+  __a->writer_section([&](_Tp volatile& __a_value){ __a_value = __val; });
+}
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_load(const volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a, int) {
+  _Tp __val;
+  __a->reader_section([&](_Tp const volatile& __a_value){ __val = __a_value; });
+  return __val;
+}
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_exchange(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a, int) {
+  _Tp __value;
+  __a->writer_section([&](_Tp volatile& __a_value){ 
+      _Tp __temp = __a_value;
+      __a_value = __value;
+      __value = __temp; 
+    });
+  return __value;
+}
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+bool __cxx_atomic_compare_exchange_strong(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a, 
+                                          _Tp* __expected, _Tp __value, int, int) {
+  bool __ret;
+  __a->writer_section([&](_Tp volatile& __a_value){ 
+      __ret = __a_value == *__expected;
+      if(__ret)
+        __a_value = __value;
+      else
+        *__expected = __a_value; });
+  return __ret;
+}
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+bool __cxx_atomic_compare_exchange_weak(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a, 
+                                        _Tp* __expected, _Tp __value, int, int) {
+  bool __ret;
+  __a->writer_section([&](_Tp volatile& __a_value){ 
+      __ret = __a_value == *__expected;
+      if(__ret)
+        __a_value = __value;
+      else
+        *__expected = __a_value; });
+  return __ret;
+}
+
+template <typename _Tp, typename _Sco, typename _Td>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_add(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a,
+                           _Td __delta, int) {
+  _Tp __old;
+  __a->writer_section([&](_Tp volatile& __a_value){ 
+      __old = __a_value;
+      __a_value += __delta; });
+  return __old;
+}
+
+template <typename _Tp, typename _Sco, typename _Td>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_sub(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a,
+                           _Td __delta, int) {
+  _Tp __old;
+  __a->writer_section([&](_Tp volatile& __a_value){ 
+      __old = __a_value;
+      __a_value -= __delta; });
+  return __old;
+}
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_and(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a,
+                           _Tp __pattern, int) {
+  _Tp __old;
+  __a->writer_section([&](_Tp volatile& __a_value){ 
+      __old = __a_value;
+      __a_value &= __pattern; });
+  return __old;
+}
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_or(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a,
+                          _Tp __pattern, int) {
+  _Tp __old;
+  __a->writer_section([&](_Tp volatile& __a_value){ 
+      __old = __a_value;
+      __a_value |= __pattern; });
+  return __old;
+}
+
+template <typename _Tp, typename _Sco>
+static _LIBCPP_INLINE_VISIBILITY inline 
+_Tp __cxx_atomic_fetch_xor(volatile __cxx_atomic_lock_impl<_Tp, _Sco>* __a,
+                           _Tp __pattern, int) {
+  _Tp __old;
+  __a->writer_section([&](_Tp volatile& __a_value){ 
+      __old = __a_value;
+      __a_value ^= __pattern; });
+  return __old;
+}
+
+template <class _Tp, class _Sco>
+using __cxx_atomic_impl = typename conditional<__atomic_always_lock_free(sizeof(_Tp), 0), 
+                                               __cxx_atomic_base_impl<_Tp, _Sco>,
+                                               __cxx_atomic_lock_impl<_Tp, _Sco>>::type;
+
+#else
+
+template <class _Tp, class _Sco>
+using __cxx_atomic_impl = __cxx_atomic_base_impl<_Tp, _Sco>;
+
+#endif //_LIBCPP_FREESTANDING && __cpp_lib_atomic_is_always_lock_free
+
 // general atomic<T>
 
-template <class _Tp, bool = is_integral<_Tp>::value && !is_same<_Tp, bool>::value>
+template <class _Tp, class _Sco = _LIBCPP_ATOMIC_SCOPE_DEFAULT, bool = is_integral<_Tp>::value && !is_same<_Tp, bool>::value>
 struct __atomic_base  // false
 {
-    mutable _Atomic(_Tp) __a_;
+    mutable __cxx_atomic_impl<_Tp, _Sco> __a_;
 
 #if defined(__cpp_lib_atomic_is_always_lock_free)
   static _LIBCPP_CONSTEXPR bool is_always_lock_free = __atomic_always_lock_free(sizeof(__a_), 0);
@@ -897,78 +1263,72 @@
 
     _LIBCPP_INLINE_VISIBILITY
     bool is_lock_free() const volatile _NOEXCEPT
-    {
-#if defined(_LIBCPP_HAS_C_ATOMIC_IMP)
-    return __c11_atomic_is_lock_free(sizeof(_Tp));
-#else
-    return __atomic_is_lock_free(sizeof(_Tp), 0);
-#endif
-    }
+        {return __cxx_atomic_is_lock_free(sizeof(_Tp));}
     _LIBCPP_INLINE_VISIBILITY
     bool is_lock_free() const _NOEXCEPT
         {return static_cast<__atomic_base const volatile*>(this)->is_lock_free();}
     _LIBCPP_INLINE_VISIBILITY
     void store(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
       _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m)
-        {__c11_atomic_store(&__a_, __d, __m);}
+        {__cxx_atomic_store(&__a_, __d, __m);}
     _LIBCPP_INLINE_VISIBILITY
     void store(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT
       _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m)
-        {__c11_atomic_store(&__a_, __d, __m);}
+        {__cxx_atomic_store(&__a_, __d, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp load(memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT
       _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m)
-        {return __c11_atomic_load(&__a_, __m);}
+        {return __cxx_atomic_load(&__a_, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp load(memory_order __m = memory_order_seq_cst) const _NOEXCEPT
       _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m)
-        {return __c11_atomic_load(&__a_, __m);}
+        {return __cxx_atomic_load(&__a_, __m);}
     _LIBCPP_INLINE_VISIBILITY
     operator _Tp() const volatile _NOEXCEPT {return load();}
     _LIBCPP_INLINE_VISIBILITY
     operator _Tp() const _NOEXCEPT          {return load();}
     _LIBCPP_INLINE_VISIBILITY
     _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_exchange(&__a_, __d, __m);}
+        {return __cxx_atomic_exchange(&__a_, __d, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_exchange(&__a_, __d, __m);}
+        {return __cxx_atomic_exchange(&__a_, __d, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_weak(_Tp& __e, _Tp __d,
                                memory_order __s, memory_order __f) volatile _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
-        {return __c11_atomic_compare_exchange_weak(&__a_, &__e, __d, __s, __f);}
+        {return __cxx_atomic_compare_exchange_weak(&__a_, &__e, __d, __s, __f);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_weak(_Tp& __e, _Tp __d,
                                memory_order __s, memory_order __f) _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
-        {return __c11_atomic_compare_exchange_weak(&__a_, &__e, __d, __s, __f);}
+        {return __cxx_atomic_compare_exchange_weak(&__a_, &__e, __d, __s, __f);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_strong(_Tp& __e, _Tp __d,
                                  memory_order __s, memory_order __f) volatile _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
-        {return __c11_atomic_compare_exchange_strong(&__a_, &__e, __d, __s, __f);}
+        {return __cxx_atomic_compare_exchange_strong(&__a_, &__e, __d, __s, __f);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_strong(_Tp& __e, _Tp __d,
                                  memory_order __s, memory_order __f) _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
-        {return __c11_atomic_compare_exchange_strong(&__a_, &__e, __d, __s, __f);}
+        {return __cxx_atomic_compare_exchange_strong(&__a_, &__e, __d, __s, __f);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_weak(_Tp& __e, _Tp __d,
                               memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_compare_exchange_weak(&__a_, &__e, __d, __m, __m);}
+        {return __cxx_atomic_compare_exchange_weak(&__a_, &__e, __d, __m, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_weak(_Tp& __e, _Tp __d,
                                memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_compare_exchange_weak(&__a_, &__e, __d, __m, __m);}
+        {return __cxx_atomic_compare_exchange_weak(&__a_, &__e, __d, __m, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_strong(_Tp& __e, _Tp __d,
                               memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_compare_exchange_strong(&__a_, &__e, __d, __m, __m);}
+        {return __cxx_atomic_compare_exchange_strong(&__a_, &__e, __d, __m, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_strong(_Tp& __e, _Tp __d,
                                  memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_compare_exchange_strong(&__a_, &__e, __d, __m, __m);}
+        {return __cxx_atomic_compare_exchange_strong(&__a_, &__e, __d, __m, __m);}
 
     _LIBCPP_INLINE_VISIBILITY
 #ifndef _LIBCPP_CXX03_LANG
@@ -992,52 +1352,56 @@
 };
 
 #if defined(__cpp_lib_atomic_is_always_lock_free)
-template <class _Tp, bool __b>
-_LIBCPP_CONSTEXPR bool __atomic_base<_Tp, __b>::is_always_lock_free;
+template <class _Tp, class _Sco, bool __b>
+_LIBCPP_CONSTEXPR bool __atomic_base<_Tp, _Sco, __b>::is_always_lock_free;
 #endif
 
 // atomic<Integral>
 
-template <class _Tp>
-struct __atomic_base<_Tp, true>
-    : public __atomic_base<_Tp, false>
+template <class _Tp, class _Sco>
+struct __atomic_base<_Tp, _Sco, true> 
+    : public __atomic_base<_Tp, _Sco, false>
 {
-    typedef __atomic_base<_Tp, false> __base;
+    typedef __atomic_base<_Tp, _Sco, false> __base;
     _LIBCPP_INLINE_VISIBILITY
-    __atomic_base() _NOEXCEPT _LIBCPP_DEFAULT
+#ifndef _LIBCPP_CXX03_LANG
+    __atomic_base() _NOEXCEPT = default;
+#else
+    __atomic_base() _NOEXCEPT : __base() {}
+#endif // _LIBCPP_CXX03_LANG
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR __atomic_base(_Tp __d) _NOEXCEPT : __base(__d) {}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_fetch_add(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_add(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_fetch_add(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_add(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_fetch_sub(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_sub(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_fetch_sub(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_sub(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_fetch_and(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_and(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_fetch_and(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_and(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_fetch_or(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_or(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_fetch_or(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_or(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_fetch_xor(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_xor(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_fetch_xor(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_xor(&this->__a_, __op, __m);}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator++(int) volatile _NOEXCEPT      {return fetch_add(_Tp(1));}
@@ -1085,7 +1449,11 @@
 {
     typedef __atomic_base<_Tp> __base;
     _LIBCPP_INLINE_VISIBILITY
-    atomic() _NOEXCEPT _LIBCPP_DEFAULT
+#ifndef _LIBCPP_CXX03_LANG
+    atomic() _NOEXCEPT = default;
+#else
+    atomic() _NOEXCEPT : __base() {}
+#endif // _LIBCPP_CXX03_LANG
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR atomic(_Tp __d) _NOEXCEPT : __base(__d) {}
 
@@ -1105,7 +1473,11 @@
 {
     typedef __atomic_base<_Tp*> __base;
     _LIBCPP_INLINE_VISIBILITY
-    atomic() _NOEXCEPT _LIBCPP_DEFAULT
+#ifndef _LIBCPP_CXX03_LANG
+    atomic() _NOEXCEPT = default;
+#else
+    atomic() _NOEXCEPT : __base() {}
+#endif // _LIBCPP_CXX03_LANG
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR atomic(_Tp* __d) _NOEXCEPT : __base(__d) {}
 
@@ -1119,17 +1491,17 @@
     _LIBCPP_INLINE_VISIBILITY
     _Tp* fetch_add(ptrdiff_t __op, memory_order __m = memory_order_seq_cst)
                                                                         volatile _NOEXCEPT
-        {return __c11_atomic_fetch_add(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_add(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* fetch_add(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_fetch_add(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_add(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* fetch_sub(ptrdiff_t __op, memory_order __m = memory_order_seq_cst)
                                                                         volatile _NOEXCEPT
-        {return __c11_atomic_fetch_sub(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_sub(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* fetch_sub(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_fetch_sub(&this->__a_, __op, __m);}
+        {return __cxx_atomic_fetch_sub(&this->__a_, __op, __m);}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator++(int) volatile _NOEXCEPT            {return fetch_add(1);}
@@ -1182,7 +1554,7 @@
 void
 atomic_init(volatile atomic<_Tp>* __o, _Tp __d) _NOEXCEPT
 {
-    __c11_atomic_init(&__o->__a_, __d);
+    __cxx_atomic_init(&__o->__a_, __d);
 }
 
 template <class _Tp>
@@ -1190,7 +1562,7 @@
 void
 atomic_init(atomic<_Tp>* __o, _Tp __d) _NOEXCEPT
 {
-    __c11_atomic_init(&__o->__a_, __d);
+    __cxx_atomic_init(&__o->__a_, __d);
 }
 
 // atomic_store
@@ -1718,20 +2090,20 @@
 
 typedef struct atomic_flag
 {
-    _Atomic(bool) __a_;
+    __cxx_atomic_impl<_LIBCPP_ATOMIC_FLAG_TYPE, _LIBCPP_ATOMIC_SCOPE_DEFAULT> __a_;
 
     _LIBCPP_INLINE_VISIBILITY
     bool test_and_set(memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {return __c11_atomic_exchange(&__a_, true, __m);}
+        {return __cxx_atomic_exchange(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(true), __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool test_and_set(memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {return __c11_atomic_exchange(&__a_, true, __m);}
+        {return __cxx_atomic_exchange(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(true), __m);}
     _LIBCPP_INLINE_VISIBILITY
     void clear(memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
-        {__c11_atomic_store(&__a_, false, __m);}
+        {__cxx_atomic_store(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(false), __m);}
     _LIBCPP_INLINE_VISIBILITY
     void clear(memory_order __m = memory_order_seq_cst) _NOEXCEPT
-        {__c11_atomic_store(&__a_, false, __m);}
+        {__cxx_atomic_store(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(false), __m);}
 
     _LIBCPP_INLINE_VISIBILITY
 #ifndef _LIBCPP_CXX03_LANG
@@ -1817,14 +2189,14 @@
 void
 atomic_thread_fence(memory_order __m) _NOEXCEPT
 {
-    __c11_atomic_thread_fence(__m);
+    __cxx_atomic_thread_fence(__m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 void
 atomic_signal_fence(memory_order __m) _NOEXCEPT
 {
-    __c11_atomic_signal_fence(__m);
+    __cxx_atomic_signal_fence(__m);
 }
 
 // Atomics for standard typedef types