diff --git a/tools/dircondenser.py b/tools/dircondenser.py
new file mode 100755
index 000000000..c87b967e7
--- /dev/null
+++ b/tools/dircondenser.py
@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+
+
+# Copyright 2018 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+'''Renames test case directories using Git from this:
+
+1 something
+3 other
+3 foo
+3 bar
+
+to this:
+
+1 something
+2 other
+3 foo
+4 bar
+
+This directory must be run from source root as it touches run_unittests.py.
+'''
+
+import os, sys, subprocess
+
+from glob import glob
+
+def get_entries():
+    entries = []
+    for e in glob('*'):
+        if not os.path.isdir(e):
+            sys.exit('Current directory must not contain any files.')
+        (number, rest) = e.split(' ', 1)
+        try:
+            number = int(number)
+        except ValueError:
+            sys.exit('Dir name %d does not start with a number.' % e)
+        entries.append((number, rest))
+    entries.sort()
+    return entries
+
+def replace_source(sourcefile, replacements):
+    with open(sourcefile, 'r') as f:
+        contents = f.read()
+    for old_name, new_name in replacements:
+        contents = contents.replace(old_name, new_name)
+    with open(sourcefile, 'w') as f:
+        f.write(contents)
+
+def condense(dirname):
+    curdir = os.getcwd()
+    os.chdir(dirname)
+    entries = get_entries()
+    replacements = []
+    for _i, e in enumerate(entries):
+        i = _i + 1
+        if e[0] != i:
+            old_name = str(e[0]) + ' ' + e[1]
+            new_name = str(i) + ' '  + e[1]
+            #print('git mv "%s" "%s"' % (old_name, new_name))
+            subprocess.check_call(['git', 'mv', old_name, new_name])
+            replacements.append((old_name, new_name))
+    os.chdir(curdir)
+    replace_source('run_unittests.py', replacements)
+    replace_source('run_project_tests.py', replacements)
+
+if __name__ == '__main__':
+    if len(sys.argv) != 1:
+        sys.exit('This script takes no arguments.')
+    for d in glob('test cases/*'):
+        condense(d)