diff --git a/libcxx/include/__atomic/aliases.h b/libcxx/include/__atomic/aliases.h
--- a/libcxx/include/__atomic/aliases.h
+++ b/libcxx/include/__atomic/aliases.h
@@ -82,7 +82,7 @@
 
 // atomic_*_lock_free : prefer the contention type most highly, then the largest lock-free type
 
-#ifdef __cpp_lib_atomic_is_always_lock_free
+#if _LIBCPP_STD_VER >= 17
 #  define _LIBCPP_CONTENTION_LOCK_FREE ::std::__libcpp_is_always_lock_free<__cxx_contention_t>::__value
 #else
 #  define _LIBCPP_CONTENTION_LOCK_FREE false
diff --git a/libcxx/include/__atomic/atomic_base.h b/libcxx/include/__atomic/atomic_base.h
--- a/libcxx/include/__atomic/atomic_base.h
+++ b/libcxx/include/__atomic/atomic_base.h
@@ -33,7 +33,7 @@
 {
     mutable __cxx_atomic_impl<_Tp> __a_;
 
-#if defined(__cpp_lib_atomic_is_always_lock_free)
+#if _LIBCPP_STD_VER >= 17
   static _LIBCPP_CONSTEXPR bool is_always_lock_free = __libcpp_is_always_lock_free<__cxx_atomic_impl<_Tp> >::__value;
 #endif
 
@@ -139,7 +139,7 @@
     __atomic_base(const __atomic_base&) = delete;
 };
 
-#if defined(__cpp_lib_atomic_is_always_lock_free)
+#if _LIBCPP_STD_VER >= 17
 template <class _Tp, bool __b>
 _LIBCPP_CONSTEXPR bool __atomic_base<_Tp, __b>::is_always_lock_free;
 #endif