diff --git a/clang/bindings/python/tests/cindex/util.py b/clang/bindings/python/tests/cindex/util.py
--- a/clang/bindings/python/tests/cindex/util.py
+++ b/clang/bindings/python/tests/cindex/util.py
@@ -77,6 +77,9 @@
 
     return cursors
 
+# Avoid configurations including '-include' from interfering with
+# our tests.
+os.environ["CLANG_NO_DEFAULT_CONFIG"] = "1"
 
 skip_if_no_fspath = unittest.skipUnless(HAS_FSPATH,
                                         "Requires file system path protocol / Python 3.6+")