diff -r 000000000000 -r 6474c204b198 build/buildconfig.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/build/buildconfig.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,30 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import imp
+import os
+import sys
+
+path = os.path.dirname(__file__)
+while not os.path.exists(os.path.join(path, 'config.status')):
+    parent = os.path.normpath(os.path.join(path, os.pardir))
+    if parent == path:
+        raise Exception("Can't find config.status")
+    path = parent
+
+path = os.path.join(path, 'config.status')
+config = imp.load_module('_buildconfig', open(path), path, ('', 'r', imp.PY_SOURCE))
+
+# Copy values from the config.status namespace into this module namespace.
+# This effectively imports topsrcdir, topobjdir, defines, substs, files,
+# headers and non_global_defines
+for var in config.__all__:
+    value = getattr(config, var)
+    if isinstance(value, list) and value and isinstance(value[0], tuple):
+        value = dict(value)
+    setattr(sys.modules[__name__], var, value)
+
+for var in os.environ:
+    if var != 'SHELL' and var in substs:
+        substs[var] = os.environ[var]