Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -387,6 +387,10 @@
 # Prevent libc++abi from having library dependencies on libc++
 add_definitions(-D_LIBCPP_DISABLE_EXTERN_TEMPLATE)
 
+# Bring back `std::unexpected`, which is removed in C++17, to support
+# pre-C++17.
+add_definitions(-D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS)
+
 if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 endif()
Index: src/cxa_exception.cpp
===================================================================
--- src/cxa_exception.cpp
+++ src/cxa_exception.cpp
@@ -11,8 +11,6 @@
 //  
 //===----------------------------------------------------------------------===//
 
-#define _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
-
 #include "cxxabi.h"
 
 #include <exception>        // for std::terminate
Index: test/test_exception_storage.pass.cpp
===================================================================
--- test/test_exception_storage.pass.cpp
+++ test/test_exception_storage.pass.cpp
@@ -7,11 +7,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-// FIXME: cxa_exception.hpp directly references `std::unexpected` and friends.
-// This breaks this test when compiled in C++17. For now fix this by manually
-// re-enabling the STL functions.
-#define _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS
-
 #include <cstdlib>
 #include <algorithm>
 #include <iostream>