diff --git a/include/__config b/include/__config
index 76675008..e951f9b1 100644
--- a/include/__config
+++ b/include/__config
@@ -64,6 +64,16 @@
 #endif  // __BIG_ENDIAN__
 #endif  // __BIG_ENDIAN__
 
+#ifdef __BYTE_ORDER__
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define _LIBCPP_LITTLE_ENDIAN 1
+#define _LIBCPP_BIG_ENDIAN 0
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define _LIBCPP_LITTLE_ENDIAN 0
+#define _LIBCPP_BIG_ENDIAN 1
+#endif // __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#endif // __BYTE_ORDER__
+
 #ifdef __FreeBSD__
 # include <sys/endian.h>
 #  if _BYTE_ORDER == _LITTLE_ENDIAN