Index: include/__config
===================================================================
--- include/__config	(revision 201037)
+++ include/__config	(working copy)
@@ -620,4 +620,12 @@
 #  define _LIBCPP_WEAK __attribute__((__weak__))
 #endif
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+#ifndef __ALIGNOF_MAX_ALIGN_T__
+typedef long double __max_align_t;
+#else
+struct _ALIGNAS(__ALIGNOF_MAX_ALIGN_T__) __max_align_t {};
+#endif
+_LIBCPP_END_NAMESPACE_STD
+
 #endif  // _LIBCPP_CONFIG
Index: include/cstddef
===================================================================
--- include/cstddef	(revision 201037)
+++ include/cstddef	(working copy)
@@ -52,7 +52,7 @@
 using ::ptrdiff_t;
 using ::size_t;
 
-typedef long double max_align_t;
+typedef _VSTD::__max_align_t max_align_t;
 
 #ifdef _LIBCPP_HAS_NO_NULLPTR