diff --git a/git_config.py b/git_config.py
index 8ded7c2..0379181 100644
--- a/git_config.py
+++ b/git_config.py
@@ -15,6 +15,8 @@
 
 from __future__ import print_function
 
+import contextlib
+import errno
 import json
 import os
 import re
@@ -502,6 +504,43 @@
     return m.group(1)
   return None
 
+@contextlib.contextmanager
+def GetUrlCookieFile(url, quiet):
+  if url.startswith('persistent-'):
+    try:
+      p = subprocess.Popen(
+          ['git-remote-persistent-https', '-print_config', url],
+          stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+          stderr=subprocess.PIPE)
+      try:
+        cookieprefix = 'http.cookiefile='
+        proxyprefix = 'http.proxy='
+        cookiefile = None
+        proxy = None
+        for line in p.stdout:
+          line = line.strip()
+          if line.startswith(cookieprefix):
+            cookiefile = line[len(cookieprefix):]
+          if line.startswith(proxyprefix):
+            proxy = line[len(proxyprefix):]
+        # Leave subprocess open, as cookie file may be transient.
+        if cookiefile or proxy:
+          yield cookiefile, proxy
+          return
+      finally:
+        p.stdin.close()
+        if p.wait():
+          err_msg = p.stderr.read()
+          if ' -print_config' in err_msg:
+            pass  # Persistent proxy doesn't support -print_config.
+          elif not quiet:
+            print(err_msg, file=sys.stderr)
+    except OSError as e:
+      if e.errno == errno.ENOENT:
+        pass  # No persistent proxy.
+      raise
+  yield GitConfig.ForUser().GetString('http.cookiefile'), None
+
 def _preconnect(url):
   m = URI_ALL.match(url)
   if m:
diff --git a/project.py b/project.py
index d82f3d7..24cac8b 100644
--- a/project.py
+++ b/project.py
@@ -13,7 +13,6 @@
 # limitations under the License.
 
 from __future__ import print_function
-import contextlib
 import errno
 import filecmp
 import glob
@@ -31,7 +30,7 @@
 
 from color import Coloring
 from git_command import GitCommand, git_require
-from git_config import GitConfig, IsId, GetSchemeFromUrl, ID_RE
+from git_config import GitConfig, IsId, GetSchemeFromUrl, GetUrlCookieFile, ID_RE
 from error import GitError, HookError, UploadError, DownloadError
 from error import ManifestInvalidRevisionError
 from error import NoManifestException
@@ -2030,7 +2029,7 @@
         os.remove(tmpPath)
     if 'http_proxy' in os.environ and 'darwin' == sys.platform:
       cmd += ['--proxy', os.environ['http_proxy']]
-    with self._GetBundleCookieFile(srcUrl, quiet) as cookiefile:
+    with GetUrlCookieFile(srcUrl, quiet) as (cookiefile, proxy):
       if cookiefile:
         cmd += ['--cookie', cookiefile, '--cookie-jar', cookiefile]
       if srcUrl.startswith('persistent-'):
@@ -2078,40 +2077,6 @@
     except OSError:
       return False
 
-  @contextlib.contextmanager
-  def _GetBundleCookieFile(self, url, quiet):
-    if url.startswith('persistent-'):
-      try:
-        p = subprocess.Popen(
-            ['git-remote-persistent-https', '-print_config', url],
-            stdin=subprocess.PIPE, stdout=subprocess.PIPE,
-            stderr=subprocess.PIPE)
-        try:
-          prefix = 'http.cookiefile='
-          cookiefile = None
-          for line in p.stdout:
-            line = line.strip()
-            if line.startswith(prefix):
-              cookiefile = line[len(prefix):]
-              break
-          # Leave subprocess open, as cookie file may be transient.
-          if cookiefile:
-            yield cookiefile
-            return
-        finally:
-          p.stdin.close()
-          if p.wait():
-            err_msg = p.stderr.read()
-            if ' -print_config' in err_msg:
-              pass  # Persistent proxy doesn't support -print_config.
-            elif not quiet:
-              print(err_msg, file=sys.stderr)
-      except OSError as e:
-        if e.errno == errno.ENOENT:
-          pass  # No persistent proxy.
-        raise
-    yield GitConfig.ForUser().GetString('http.cookiefile')
-
   def _Checkout(self, rev, quiet=False):
     cmd = ['checkout']
     if quiet:
diff --git a/subcmds/sync.py b/subcmds/sync.py
index 652a0c0..0fc493c 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -23,18 +23,26 @@
 import socket
 import subprocess
 import sys
+import tempfile
 import time
 
 from pyversion import is_python3
 if is_python3():
+  import http.cookiejar as cookielib
+  import urllib.error
   import urllib.parse
+  import urllib.request
   import xmlrpc.client
 else:
+  import cookielib
   import imp
+  import urllib2
   import urlparse
   import xmlrpclib
   urllib = imp.new_module('urllib')
+  urllib.error = urllib2
   urllib.parse = urlparse
+  urllib.request = urllib2
   xmlrpc = imp.new_module('xmlrpc')
   xmlrpc.client = xmlrpclib
 
@@ -57,6 +65,7 @@
   multiprocessing = None
 
 from git_command import GIT, git_require
+from git_config import GetSchemeFromUrl, GetUrlCookieFile
 from git_refs import R_HEADS, HEAD
 import gitc_utils
 from project import Project
@@ -598,8 +607,12 @@
                                                     (username, password),
                                                     1)
 
+      transport = PersistentTransport(manifest_server)
+      if manifest_server.startswith('persistent-'):
+        manifest_server = manifest_server[len('persistent-'):]
+
       try:
-        server = xmlrpc.client.Server(manifest_server)
+        server = xmlrpc.client.Server(manifest_server, transport=transport)
         if opt.smart_sync:
           p = self.manifest.manifestProject
           b = p.GetBranch(p.CurrentBranch)
@@ -879,3 +892,93 @@
         os.remove(self._path)
       except OSError:
         pass
+
+# This is a replacement for xmlrpc.client.Transport using urllib2
+# and supporting persistent-http[s]. It cannot change hosts from
+# request to request like the normal transport, the real url
+# is passed during initialization.
+class PersistentTransport(xmlrpc.client.Transport):
+  def __init__(self, orig_host):
+    self.orig_host = orig_host
+
+  def request(self, host, handler, request_body, verbose=False):
+    with GetUrlCookieFile(self.orig_host, not verbose) as (cookiefile, proxy):
+      # Python doesn't understand cookies with the #HttpOnly_ prefix
+      # Since we're only using them for HTTP, copy the file temporarily,
+      # stripping those prefixes away.
+      tmpcookiefile = tempfile.NamedTemporaryFile()
+      try:
+        with open(cookiefile) as f:
+          for line in f:
+            if line.startswith("#HttpOnly_"):
+              line = line[len("#HttpOnly_"):]
+            tmpcookiefile.write(line)
+        tmpcookiefile.flush()
+
+        cookiejar = cookielib.MozillaCookieJar(tmpcookiefile.name)
+        cookiejar.load()
+      finally:
+        tmpcookiefile.close()
+
+      proxyhandler = urllib.request.ProxyHandler
+      if proxy:
+        proxyhandler = urllib.request.ProxyHandler({
+            "http": proxy,
+            "https": proxy })
+
+      opener = urllib.request.build_opener(
+          urllib.request.HTTPCookieProcessor(cookiejar),
+          proxyhandler)
+
+      url = urllib.parse.urljoin(self.orig_host, handler)
+      parse_results = urllib.parse.urlparse(url)
+
+      scheme = parse_results.scheme
+      if scheme == 'persistent-http':
+        scheme = 'http'
+      if scheme == 'persistent-https':
+        # If we're proxying through persistent-https, use http. The
+        # proxy itself will do the https.
+        if proxy:
+          scheme = 'http'
+        else:
+          scheme = 'https'
+
+      # Parse out any authentication information using the base class
+      host, extra_headers, _ = self.get_host_info(parse_results.netloc)
+
+      url = urllib.parse.urlunparse((
+          scheme,
+          host,
+          parse_results.path,
+          parse_results.params,
+          parse_results.query,
+          parse_results.fragment))
+
+      request = urllib.request.Request(url, request_body)
+      if extra_headers is not None:
+        for (name, header) in extra_headers:
+          request.add_header(name, header)
+      request.add_header('Content-Type', 'text/xml')
+      try:
+        response = opener.open(request)
+      except urllib.error.HTTPError as e:
+        if e.code == 501:
+          # We may have been redirected through a login process
+          # but our POST turned into a GET. Retry.
+          response = opener.open(request)
+        else:
+          raise
+
+      p, u = xmlrpc.client.getparser()
+      while 1:
+        data = response.read(1024)
+        if not data:
+          break
+        p.feed(data)
+      p.close()
+      return u.close()
+
+  def close(self):
+    pass
+