--- llvm-10.0.0.src/projects/libcxx/include/__config.orig	2020-04-28 09:59:15.000000000 -0700
+++ llvm-10.0.0.src/projects/libcxx/include/__config	2020-04-28 10:00:33.000000000 -0700
@@ -10,6 +10,10 @@
 #ifndef _LIBCPP_CONFIG
 #define _LIBCPP_CONFIG
 
+// for MacPorts, our installed libcxx does not require Apple system
+// Availability tests
+#define _LIBCPP_DISABLE_AVAILABILITY
+
 #if defined(_MSC_VER) && !defined(__clang__)
 #  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #    define _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
