diff --git a/cbuildbot/stages/sync_stages.py b/cbuildbot/stages/sync_stages.py
index 3b3dc95..eb9fdcb 100644
--- a/cbuildbot/stages/sync_stages.py
+++ b/cbuildbot/stages/sync_stages.py
@@ -13,6 +13,7 @@
 import itertools
 import os
 import re
+import shutil
 import sys
 import time
 from xml.etree import ElementTree
@@ -386,6 +387,20 @@
 
   def _InitializeRepo(self):
     """Set up the RepoRepository object."""
+    # If we have no repository at all, but we have a warm cache path, copy in
+    # the warm cache. This is done so builders can try to avoid doing a sync
+    # from scratch on a new builder (especially GCE instances).
+    if (not repository.IsARepoRoot(self._build_root) and
+        self.options.repo_cache and
+        os.path.isdir(self.options.repo_cache)):
+      # If the warm cache is invalid the wrong branch, or from the wrong
+      # manifest, Repository will repair it.
+      logging.info('Using warm cache "%s" to populate buildroot "%s"',
+                   self.options.repo_cache,
+                   self._build_root)
+      shutil.copytree(self.options.repo_cache,
+                      self._build_root)
+
     self.repo = self.GetRepoRepository()
 
   def GetNextManifest(self):
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index aa0acb2..de8da2b 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -519,6 +519,10 @@
                                 'to skip verification by the bootstrap code'))
   group.add_remote_option('--buildbot', dest='buildbot', action='store_true',
                           default=False, help='This is running on a buildbot')
+  parser.add_remote_option('--repo-cache', type='path',
+                           help='Directory from which to copy a repo checkout '
+                                'if our build root is empty, to avoid '
+                                'excessive GoB load with a fresh sync.')
   group.add_remote_option('--no-buildbot-tags', action='store_false',
                           dest='enable_buildbot_tags', default=True,
                           help='Suppress buildbot specific tags from log '