diff --git a/tests/hghave.py b/tests/hghave.py
--- a/tests/hghave.py
+++ b/tests/hghave.py
@@ -611,7 +611,14 @@
 def has_clang_format():
     m = matchoutput('clang-format --version', br'clang-format version (\d+)')
     # style changed somewhere between 10.x and 11.x
-    return m and int(m.group(1)) >= 11
+    if m:
+        return int(m.group(1)) >= 11
+    # Assist Googler contributors, they have a centrally-maintained version of
+    # clang-format that is generally very fresh, but unlike most builds (both
+    # official and unofficial), it does *not* include a version number.
+    return matchoutput(
+        'clang-format --version', br'clang-format .*google3-trunk \([0-9a-f]+\)'
+    )
 
 
 @check("jshint", "JSHint static code analysis tool")