Index: clang-tidy/tool/run-clang-tidy.py
===================================================================
--- clang-tidy/tool/run-clang-tidy.py
+++ clang-tidy/tool/run-clang-tidy.py
@@ -67,6 +67,11 @@
     result += '../'
   return os.path.realpath(result)
 
+def make_absolute(f, directory):
+  if os.path.isabs(f):
+    return f
+  return os.path.normpath(os.path.join(directory, f))
+
 
 def get_tidy_invocation(f, clang_tidy_binary, checks, tmpdir, build_path,
                         header_filter, extra_arg, extra_arg_before, quiet):
@@ -223,7 +228,8 @@
 
   # Load the database and extract all files.
   database = json.load(open(os.path.join(build_path, db_path)))
-  files = [entry['file'] for entry in database]
+  files = [make_absolute(entry['file'], entry['directory'])
+          for entry in database]
 
   max_task = args.j
   if max_task == 0: