diff --git a/binhost_clobber.py b/binhost_clobber.py
new file mode 100755
index 0000000000..048429dd9d
--- /dev/null
+++ b/binhost_clobber.py
@@ -0,0 +1,92 @@
+#!/usr/bin/python
+# Copyright (c) 2009 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Script to grab a list of ebuilds which cannot be safely mirrored.
+
+Some ebuilds do not have the proper versioning magic to be able to be safely
+mirrored. We would like to phase them out gradually, by updating a list which
+can be safely cached.
+"""
+
+import os
+import re
+import StringIO
+import tarfile
+import urllib
+
+
+def main():
+  # Get a tarball of chromiumos-overlay.
+  fh = urllib.urlopen('http://src.chromium.org/cgi-bin/gitweb.cgi?'
+                      'p=chromiumos-overlay.git;a=snapshot;h=HEAD;sf=tgz')
+  tgz = fh.read()
+  fh.close()
+
+  # Prepare a set of files to clobber.
+  clobber_list = set()
+  # Prepare a set of files to exempt from clobbering.
+  exempt_list = set()
+
+  # Walk the tarball looking for SAFE_TO_CACHE lists and ebuilds containing
+  # CHROMEOS_ROOT.
+  tgzf = StringIO.StringIO(tgz)
+  tar = tarfile.open(fileobj=tgzf, mode='r')
+  for tinfoi in tar:
+    if not tinfoi.isdir():
+      original_name = tinfoi.name
+      tinfo = tinfoi
+      while tinfo.islnk() or tinfo.issym():
+        path = os.path.normpath(os.path.join(os.path.dirname(tinfo.name),
+                                             tinfo.linkname)) 
+        tinfo = tar.getmember(path)
+      if tinfo.name.endswith('.ebuild'):
+        # Load each ebuild.
+        fh = tar.extractfile(tinfo)
+        ebuild_data = fh.read()
+        fh.close()
+        # Add to the clobber list if it contains CHROMEOS_ROOT.
+        if 'CHROMEOS_ROOT' in ebuild_data:
+          filename = os.path.split(original_name)[1]
+          basename = os.path.splitext(filename)[0]
+          clobber_list.add(basename)
+      elif tinfo.name.endswith('/SAFE_TO_CACHE'):
+        fh = tar.extractfile(tinfo)
+        for line in fh:
+          if len(line) > 1 and line[0] != '#':
+            exempt_list.add(line.strip())
+        fh.close()
+  tar.close()
+  tgzf.close()
+
+  # Don't clobber ebuilds listed in SAFE_TO_CACHE.
+  clobber_list -= exempt_list
+
+  # Scan the current directory for any Packages files, modify to remove
+  # packages that shouldn't be cached.
+  for root, _, files in os.walk('.', topdown=False):
+    for name in files:
+      filename = os.path.join(root, name)
+      basename = os.path.split(filename)[1]
+      if basename == 'Packages':
+        # Filter out entries involving uncache-able ebuilds.
+        allowed = True
+        nlines = []
+        fh = open(filename, 'r')
+        for line in fh:
+          m = re.match('^CPV\: [^\n]+/([^/]+)[\n]$', line)
+          if m:
+            allowed = m.group(1) not in clobber_list
+          if allowed:
+            nlines.append(line)
+        fh.close()
+        # Write out new contents.
+        fh = open(filename, 'w')
+        for line in nlines:
+          fh.write(line)
+        fh.close()
+
+
+if __name__ == '__main__':
+  main()