diff --git a/git_command.py b/git_command.py
index 95db91f..5d73c28 100644
--- a/git_command.py
+++ b/git_command.py
@@ -169,7 +169,8 @@
                disable_editor=False,
                ssh_proxy=None,
                cwd=None,
-               gitdir=None):
+               gitdir=None,
+               objdir=None):
     env = self._GetBasicEnv()
 
     if disable_editor:
@@ -194,13 +195,24 @@
         cwd = project.worktree
       if not gitdir:
         gitdir = project.gitdir
+    # Git on Windows wants its paths only using / for reliability.
+    if platform_utils.isWindows():
+      if objdir:
+        objdir = objdir.replace('\\', '/')
+      if gitdir:
+        gitdir = gitdir.replace('\\', '/')
+
+    if objdir:
+      # Set to the place we want to save the objects.
+      env['GIT_OBJECT_DIRECTORY'] = objdir
+      if gitdir:
+        # Allow git to search the original place in case of local or unique refs
+        # that git will attempt to resolve even if we aren't fetching them.
+        env['GIT_ALTERNATE_OBJECT_DIRECTORIES'] = gitdir + '/objects'
 
     command = [GIT]
     if bare:
       if gitdir:
-        # Git on Windows wants its paths only using / for reliability.
-        if platform_utils.isWindows():
-          gitdir = gitdir.replace('\\', '/')
         env[GIT_DIR] = gitdir
       cwd = None
     command.append(cmdv[0])
@@ -234,6 +246,11 @@
         dbg += ': export GIT_DIR=%s\n' % env[GIT_DIR]
         LAST_GITDIR = env[GIT_DIR]
 
+      if 'GIT_OBJECT_DIRECTORY' in env:
+        dbg += ': export GIT_OBJECT_DIRECTORY=%s\n' % env['GIT_OBJECT_DIRECTORY']
+      if 'GIT_ALTERNATE_OBJECT_DIRECTORIES' in env:
+        dbg += ': export GIT_ALTERNATE_OBJECT_DIRECTORIES=%s\n' % env['GIT_ALTERNATE_OBJECT_DIRECTORIES']
+
       dbg += ': '
       dbg += ' '.join(command)
       if stdin == subprocess.PIPE:
diff --git a/project.py b/project.py
index 8598de3..b70f6d4 100644
--- a/project.py
+++ b/project.py
@@ -2192,8 +2192,10 @@
     retry_cur_sleep = retry_sleep_initial_sec
     ok = prune_tried = False
     for try_n in range(retry_fetches):
-      gitcmd = GitCommand(self, cmd, bare=True, ssh_proxy=ssh_proxy,
-                          merge_output=True, capture_stdout=quiet or bool(output_redir))
+      gitcmd = GitCommand(
+          self, cmd, bare=True, objdir=os.path.join(self.objdir, 'objects'),
+          ssh_proxy=ssh_proxy,
+          merge_output=True, capture_stdout=quiet or bool(output_redir))
       if gitcmd.stdout and not quiet and output_redir:
         output_redir.write(gitcmd.stdout)
       ret = gitcmd.Wait()
@@ -2309,7 +2311,8 @@
       cmd.append(str(f))
     cmd.append('+refs/tags/*:refs/tags/*')
 
-    ok = GitCommand(self, cmd, bare=True).Wait() == 0
+    ok = GitCommand(
+        self, cmd, bare=True, objdir=os.path.join(self.objdir, 'objects')).Wait() == 0
     platform_utils.remove(bundle_dst, missing_ok=True)
     platform_utils.remove(bundle_tmp, missing_ok=True)
     return ok