diff --git a/buildbot/cbuildbot_commands.py b/buildbot/cbuildbot_commands.py
index 68a83f6..f6d73ee 100644
--- a/buildbot/cbuildbot_commands.py
+++ b/buildbot/cbuildbot_commands.py
@@ -162,6 +162,7 @@
     buildroot: buildroot to clean up.
   """
   lock_path = os.path.join(buildroot, '.clean_lock')
+  deleted_paths = multiprocessing.Event()
 
   def RunCleanupCommands(project, cwd):
     with locking.FileLock(lock_path, verbose=False).read_lock() as lock:
@@ -180,6 +181,7 @@
         logging.warn('\n%s', result.error)
         logging.warn('Deleting %s because %s failed', cwd, e.result.cmd)
         lock.write_lock()
+        deleted_paths.set()
         osutils.RmDir(cwd, ignore_missing=True)
         # Delete the backing stores as well.
         for store in (repo_git_store, repo_obj_store):
@@ -196,6 +198,13 @@
           git.ManifestCheckout.Cached(buildroot).ListCheckouts()]
   parallel.RunTasksInProcessPool(RunCleanupCommands, dirs)
 
+  # repo shares git object directories amongst multiple project paths. If the
+  # first pass deleted an object dir for a project path, then other repositories
+  # (project paths) of that same project may now be broken. Do a second pass to
+  # clean them up as well.
+  if deleted_paths.is_set():
+    parallel.RunTasksInProcessPool(RunCleanupCommands, dirs)
+
 
 def CleanUpMountPoints(buildroot):
   """Cleans up any stale mount points from previous runs."""