Index: clang-tools-extra/clang-tidy/tool/tidy-llvm.py
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/tool/tidy-llvm.py
@@ -0,0 +1,100 @@
+#!/usr/bin/env python
+#
+#===- tidy-llvm  --------------------------------------------*- python -*--===#
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===-----------------------------------------------------------------------===#
+
+
+"""
+tidy-llvm
+==========================
+
+Runs clang-tidy over named .cpp and .h files.
+tidy-llvm must be run from inside an LLVM source tree.
+But otherwise, it finds the root of the llvm tree, verifies build requirements,
+constructs include paths, concatenates an argument list and then runs clang-tidy.
+clang-tidy will in turn examine any .clang-tidy in the path
+"""
+
+import os
+import sys
+
+def fail(s):
+  print(s)
+  sys.exit(1)
+
+def file_exists(name):
+  if not os.path.isfile(name):
+    fail('Cannot find ' + name)
+  return name
+
+def dir_exists(name):
+  if not os.path.isdir(name):
+    fail('Cannot find ' + name)
+  return name
+
+def find_llvm_root():
+  result = './'
+  while not os.path.isdir(os.path.join(result, "build")):
+    if os.path.realpath(result) == '/':
+      fail('Error: could not find llvm root.')
+    result += '../'
+  return os.path.realpath(result)
+
+# LLVM_ENABLE_PROJECTS:STRING=clang;clang-tools-extra
+# CMAKE_EXPORT_COMPILE_COMMANDS:UNINITIALIZED=On
+
+def verify_config(root):
+  found = 0
+  for line in open(file_exists(os.path.join(root, "build/CMakeCache.txt")), 'r'):
+    if "LLVM_ENABLE_PROJECTS:STRING=" in line:
+      if "clang;clang-tools-extra" not in line:
+        fail('Build needs clang;clang-tools-extra')
+      found = 1
+      break
+  if not found:
+    fail('Build needs clang;clang-tools-extra')
+  for line in open(file_exists(os.path.join(root, "build/CMakeCache.txt")), 'r'):
+    if "CMAKE_EXPORT_COMPILE_COMMANDS:UNINITIALIZED=On" in line:
+      return
+  fail('Build needs CMAKE_EXPORT_COMPILE_COMMANDS:UNINITIALIZED=On')
+
+def construct_llvm_include_paths(root):
+  libcxx = dir_exists(os.path.join(root, "libcxx/include"))
+  build_include = dir_exists(os.path.join(root, "build/include"))
+  llvm_include = dir_exists(os.path.join(root, "llvm/include"))
+  return "-I" + libcxx + " -I" + build_include + " -I" + llvm_include
+
+def construct_current_include_paths():
+  paths = ""
+  for e in os.listdir():
+    if os.path.isdir(e):
+      paths += " -I" + e
+  return paths
+
+def process_args(root, cmd_args):
+  for name in cmd_args:
+    if not name.endswith(".h") and not name.endswith(".cpp"):
+      fail(name + " does not end with .h or .cpp")
+    file_exists(name)
+  return " ".join(str(f) for f in cmd_args)
+
+def main():
+  root = find_llvm_root()
+  verify_config(root)
+  llvm_include_paths = construct_llvm_include_paths(root)
+  current_include_paths = construct_current_include_paths()
+  if len(sys.argv) == 1:
+    fail("tidy-llvm: [.cpp and .h files]")
+  args = process_args(root, sys.argv[1:])
+  cmd = ("clang-tidy -checks=\"llvm-*\" -p "
+	+ os.path.join(root, "build") + " " + args + " -- -I."
+	+ current_include_paths + " " + llvm_include_paths)
+  os.system(cmd)
+
+if __name__ == '__main__':
+  main()