diff --git a/gclient.py b/gclient.py
index 3ac66e7639..33f7911f0f 100755
--- a/gclient.py
+++ b/gclient.py
@@ -1738,6 +1738,9 @@ def CMDsync(parser, args):
   parser.add_option('--output-json',
                     help='Output a json document to this path containing '
                          'summary information about the sync.')
+  parser.add_option('--shallow', action='store_true',
+                    help='GIT ONLY - Do a shallow clone into the cache dir. '
+                         'Requires Git 1.9+')
   (options, args) = parser.parse_args(args)
   client = GClient.LoadCurrentConfig(options)
 
diff --git a/gclient_scm.py b/gclient_scm.py
index 00b8145bb4..594515dc16 100644
--- a/gclient_scm.py
+++ b/gclient_scm.py
@@ -765,7 +765,15 @@ class GitWrapper(SCMWrapper):
     if hasattr(options, 'with_branch_heads') and options.with_branch_heads:
       mirror_kwargs['refs'].append('refs/branch-heads/*')
     mirror = git_cache.Mirror(url, **mirror_kwargs)
-    mirror.populate(verbose=options.verbose, bootstrap=True)
+    if options.shallow:
+      # HACK(hinoka): These repositories should be super shallow.
+      if 'flash' in url:
+        depth = 10
+      else:
+        depth = 10000
+    else:
+      depth = None
+    mirror.populate(verbose=options.verbose, bootstrap=True, depth=depth)
     mirror.unlock()
     return mirror.mirror_path if mirror.exists() else None