Index: libcxx/include/__config
===================================================================
--- libcxx/include/__config
+++ libcxx/include/__config
@@ -92,7 +92,8 @@
 // instead of as a class simulating an enum. If this option is enabled
 // `pointer_safety` and `get_pointer_safety()` will no longer be available
 // in C++03.
-#  define _LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE
+// The underlying type of the typed enumeration is "unsigned char".
+#  define _LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE unsigned char
 // Define a key function for `bad_function_call` in the library, to centralize
 // its vtable and typeinfo to libc++ rather than having all other libraries
 // using that class define their own copies.
@@ -127,6 +128,12 @@
 #  if defined(__FreeBSD__)
 #    define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
 #  endif
+
+#  if defined(_AIX)
+// AIX used C++11 strongly typed enumeration with underlying type as "int"
+// for `pointer_safety`.
+#    define _LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE int
+#  endif
 #endif
 
 #if defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCPP_ABI_UNSTABLE) || _LIBCPP_ABI_VERSION >= 2
Index: libcxx/include/memory
===================================================================
--- libcxx/include/memory
+++ libcxx/include/memory
@@ -4076,7 +4076,7 @@
 //enum class
 #if defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE)
 # ifndef _LIBCPP_CXX03_LANG
-enum class pointer_safety : unsigned char {
+enum class pointer_safety : _LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE {
   relaxed,
   preferred,
   strict
Index: libcxx/test/libcxx/utilities/memory/util.dynamic.safety/get_pointer_safety_new_abi.pass.cpp
===================================================================
--- libcxx/test/libcxx/utilities/memory/util.dynamic.safety/get_pointer_safety_new_abi.pass.cpp
+++ libcxx/test/libcxx/utilities/memory/util.dynamic.safety/get_pointer_safety_new_abi.pass.cpp
@@ -13,7 +13,7 @@
 // The pointer_safety interface is no longer provided in C++03 in the new ABI.
 // XFAIL: c++03
 
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE="unsigned char"
 
 #include <memory>
 #include <cassert>