diff --git a/clang/test/utils/update_cc_test_checks/lit.local.cfg b/clang/test/utils/update_cc_test_checks/lit.local.cfg
--- a/clang/test/utils/update_cc_test_checks/lit.local.cfg
+++ b/clang/test/utils/update_cc_test_checks/lit.local.cfg
@@ -21,8 +21,10 @@
                            'update_cc_test_checks.py')
 assert os.path.isfile(script_path)
 # Windows: llvm-lit.py, Linux: llvm-lit
-llvm_lit = glob.glob(os.path.join(config.llvm_tools_dir, 'llvm-lit*'))[0]
-lit = config.llvm_external_lit if config.llvm_external_lit else shell_quote(llvm_lit)
+if config.llvm_external_lit:
+    lit = config.llvm_external_lit
+else:
+    lit = shell_quote(glob.glob(os.path.join(config.llvm_tools_dir, 'llvm-lit*'))[0])
 python = shell_quote(config.python_executable)
 config.substitutions.append(
     ('%update_cc_test_checks', "%s %s %s" % (