diff --git a/test/libcxx/test/config.py b/test/libcxx/test/config.py
index b00f74fa7..40defdff5 100644
--- a/test/libcxx/test/config.py
+++ b/test/libcxx/test/config.py
@@ -450,9 +450,11 @@ class Configuration(object):
             self.lit_config.fatal("cxx_headers='%s' is not a directory."
                                   % cxx_headers)
         self.cxx.compile_flags += ['-I' + cxx_headers]
-        cxxabi_headers = os.path.join(self.libcxx_obj_root, 'include', 'c++-build')
-        if os.path.isdir(cxxabi_headers):
-            self.cxx.compile_flags += ['-I' + cxxabi_headers]
+        if self.libcxx_obj_root is not None:
+            cxxabi_headers = os.path.join(self.libcxx_obj_root, 'include',
+                                          'c++-build')
+            if os.path.isdir(cxxabi_headers):
+                self.cxx.compile_flags += ['-I' + cxxabi_headers]
 
     def configure_config_site_header(self):
         # Check for a possible __config_site in the build directory. We