diff --git a/git_cache.py b/git_cache.py
index 7a6c907d47..4a2a237411 100755
--- a/git_cache.py
+++ b/git_cache.py
@@ -258,10 +258,6 @@ class Mirror(object):
     # Not recognized.
     return None
 
-  @property
-  def gs_folder(self):
-    return 'gs://%s/v2/%s' % (self.bootstrap_bucket, self.basedir)
-
   @classmethod
   def FromPath(cls, path):
     return cls(cls.CacheDirToUrl(path))
@@ -604,43 +600,28 @@ class Mirror(object):
         lockfile.unlock()
 
   def update_bootstrap(self, prune=False):
-    # The folder is <git number>
+    # The files are named <git number>.zip
     gen_number = subprocess.check_output(
         [self.git_exe, 'number', 'master'], cwd=self.mirror_path).strip()
     # Run Garbage Collect to compress packfile.
     self.RunGit(['gc', '--prune=all'])
-
+    # Creating a temp file and then deleting it ensures we can use this name.
+    _, tmp_zipfile = tempfile.mkstemp(suffix='.zip')
+    os.remove(tmp_zipfile)
+    subprocess.call(['zip', '-r', tmp_zipfile, '.'], cwd=self.mirror_path)
     gsutil = Gsutil(path=self.gsutil_exe, boto_path=None)
-
-    src_name = self.mirror_path
-    dest_name = '%s/%s' % (self.gs_folder, gen_number)
-
-    # check to see if folder already exists in gs
-    _, ls_out, ls_err = gsutil.check_call('ls', dest_name)
-    _, ls_out_ready, ls_err_ready = (
-      gsutil.check_call('ls', dest_name + '.ready'))
-    
-    if ls_err:
-      print('Failed to check GS:\n%s' % (ls_err))
-      return
-
-    if ls_err_ready:
-      print('Failed to check GS:\n%s' % (ls_err_ready))
-      return
-
-    if not (ls_out == '' and ls_out_ready == ''):
-      return
-
-    gsutil.call('-m', 'cp', '-r', src_name, dest_name)
-
-    #TODO(karenqian): prune old caches
-
-    # create .ready file and upload
-    _, ready_file_name =  tempfile.mkstemp(suffix='.ready')
-    try:
-      gsutil.call('cp', ready_file_name, '%s.ready' % (dest_name))
-    finally:
-      os.remove(ready_file_name)
+    gs_folder = 'gs://%s/%s' % (self.bootstrap_bucket, self.basedir)
+    dest_name = '%s/%s.zip' % (gs_folder, gen_number)
+    gsutil.call('cp', tmp_zipfile, dest_name)
+    os.remove(tmp_zipfile)
+
+    # Remove all other files in the same directory.
+    if prune:
+      _, ls_out, _ = gsutil.check_call('ls', gs_folder)
+      for filename in ls_out.splitlines():
+        if filename == dest_name:
+          continue
+        gsutil.call('rm', filename)
 
   @staticmethod
   def DeleteTmpPackFiles(path):