Index: run-clang-tidy.py
===================================================================
--- run-clang-tidy.py
+++ run-clang-tidy.py
@@ -45,6 +45,8 @@
 import sys
 import tempfile
 import threading
+import yaml
+import glob
 
 
 def find_compilation_database(path):
@@ -87,14 +89,37 @@
   return start
 
 
+def merge_replacement_files(tmpdir, fixfile):
+  """Merge all replacement files in a directory into a single fixfile"""
+  merged={ 'MainSourceFile': None, 'Replacements': [] }
+
+  for replacefile in glob.iglob(tmpdir + '/*.yaml'):
+    with open(replacefile, 'r') as f:
+      content = yaml.safe_load(f)
+      if not content: continue # Skip empty files
+
+    try:
+      if not merged['MainSourceFile']:
+        merged['MainSourceFile'] = content['MainSourceFile']
+      elif merged['MainSourceFile'] != content['MainSourceFile']:
+        # The values given for MainSourceFile are inconsistent.
+        # Just empty MainSourceFile blank:
+        merged['MainSourceFile']=''
+      merged['Replacements'].extend(content['Replacements'])
+    except KeyError:
+      pass # Ignore files with missing keys
+
+  if merged['Replacements']:
+    with open(fixfile,'w') as out:
+      yaml.safe_dump(merged, out)
+
 def apply_fixes(args, tmpdir):
-  """Calls clang-apply-fixes on a given directory. Deletes the dir when done."""
+  """Calls clang-apply-fixes on a given directory."""
   invocation = [args.clang_apply_replacements_binary]
   if args.format:
     invocation.append('-format')
   invocation.append(tmpdir)
   subprocess.call(invocation)
-  shutil.rmtree(tmpdir)
 
 
 def run_tidy(args, tmpdir, build_path, queue):
@@ -129,6 +154,9 @@
                       'headers to output diagnostics from. Diagnostics from '
                       'the main file of each translation unit are always '
                       'displayed.')
+  parser.add_argument('-export-fixes', metavar='filename', dest='export_fixes',
+                      help='Create a yaml file to store suggested fixes in, '
+                      'which can be applied with clang-apply-replacements')
   parser.add_argument('-j', type=int, default=0,
                       help='number of tidy instances to be run in parallel.')
   parser.add_argument('files', nargs='*', default=['.*'],
@@ -178,7 +206,7 @@
     max_task = multiprocessing.cpu_count()
 
   tmpdir = None
-  if args.fix:
+  if args.fix or args.export_fixes:
     tmpdir = tempfile.mkdtemp()
 
   # Build up a big regexy filter from all command line arguments.
@@ -205,13 +233,20 @@
     # This is a sad hack. Unfortunately subprocess goes
     # bonkers with ctrl-c and we start forking merrily.
     print '\nCtrl-C detected, goodbye.'
-    if args.fix:
+    if tmpdir:
       shutil.rmtree(tmpdir)
     os.kill(0, 9)
 
+  if args.export_fixes:
+    print 'Writing fixes to ' + args.export_fixes
+    merge_replacement_files(tmpdir,args.export_fixes)
+
   if args.fix:
     print 'Applying fixes ...'
     apply_fixes(args, tmpdir)
 
+  if tmpdir:
+    shutil.rmtree(tmpdir)
+
 if __name__ == '__main__':
   main()