diff --git a/git_cl.py b/git_cl.py
index a47da6d..59c2d4b 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -1495,6 +1495,16 @@
     return 1
   if CHANGE_ID not in change_desc.description:
     AddChangeIdToCommitMessage(options, args)
+
+  commits = RunGit(['rev-list', '%s/%s...' % (remote, branch)]).splitlines()
+  if len(commits) > 1:
+    print('WARNING: This will upload %d commits. Run the following command '
+          'to see which commits will be uploaded: ' % len(commits))
+    print('git log %s/%s...' % (remote, branch))
+    print('You can also use `git squash-branch` to squash these into a single'
+          'commit.')
+    ask_for_data('About to upload; enter to confirm.')
+
   if options.reviewers:
     change_desc.update_reviewers(options.reviewers)
 
diff --git a/tests/git_cl_test.py b/tests/git_cl_test.py
index 9234fb2..2d20440 100755
--- a/tests/git_cl_test.py
+++ b/tests/git_cl_test.py
@@ -588,6 +588,7 @@
            description)
           ]
     calls += [
+        ((['git', 'rev-list', 'origin/master...'],), ''),
         ((['git', 'config', 'rietveld.cc'],), '')
         ]
     receive_pack = '--receive-pack=git receive-pack '