diff --git a/include/__config b/include/__config
index db5a832b6..edda3c5e3 100644
--- a/include/__config
+++ b/include/__config
@@ -27,7 +27,7 @@
 #define _GNUC_VER 0
 #endif
 
-#define _LIBCPP_VERSION 3800
+#define _LIBCPP_VERSION 3900
 
 #ifndef _LIBCPP_ABI_VERSION
 #define _LIBCPP_ABI_VERSION 1