diff --git a/libcxx/utils/libcxx/test/config.py b/libcxx/utils/libcxx/test/config.py
--- a/libcxx/utils/libcxx/test/config.py
+++ b/libcxx/utils/libcxx/test/config.py
@@ -336,7 +336,8 @@
         support_path = os.path.join(self.libcxx_src_root, 'test', 'support')
         self.configure_config_site_header()
         if self.cxx_stdlib_under_test != 'libstdc++' and \
-           not self.target_info.is_windows():
+           not self.target_info.is_windows() and \
+           not self.target_info.is_zos():
             self.cxx.compile_flags += [
                 '-include', os.path.join(support_path, 'nasty_macros.h')]
         if self.cxx_stdlib_under_test == 'msvc':
diff --git a/libcxx/utils/libcxx/test/target_info.py b/libcxx/utils/libcxx/test/target_info.py
--- a/libcxx/utils/libcxx/test/target_info.py
+++ b/libcxx/utils/libcxx/test/target_info.py
@@ -27,6 +27,9 @@
     def is_windows(self):
         return False
 
+    def is_zos(self):
+        return False
+
     def is_mingw(self):
         return False
 
@@ -193,6 +196,13 @@
     def is_windows(self):
         return True
 
+class ZOSLocalTI(DefaultTargetInfo):
+    def __init__(self, full_config):
+        super(ZOSLocalTI, self).__init__(full_config)
+
+    def is_zos(self):
+        return True
+
 class MingwLocalTI(WindowsLocalTI):
     def __init__(self, full_config):
         super(MingwLocalTI, self).__init__(full_config)
@@ -215,4 +225,5 @@
     if target_system == 'NetBSD':  return NetBSDLocalTI(full_config)
     if target_system == 'Linux':   return LinuxLocalTI(full_config)
     if target_system == 'Windows': return WindowsLocalTI(full_config)
+    if target_system == 'OS/390':  return ZOSLocalTI(full_config)
     return DefaultTargetInfo(full_config)