diff --git a/bin/cbuildbot.py b/bin/cbuildbot.py
index ad0c073698..c75e467cc7 100755
--- a/bin/cbuildbot.py
+++ b/bin/cbuildbot.py
@@ -532,7 +532,8 @@ def _ResolveOverlays(buildroot, overlays):
   elif overlays == 'both':
     paths = [public_overlay, private_overlay]
   else:
-    Die('Incorrect overlay configuration: %s' % overlays)
+    Info('No overlays found.')
+    paths = []
   return paths
 
 
@@ -623,11 +624,18 @@ def main():
 
   try:
     # Calculate list of overlay directories.
-    overlays = _ResolveOverlays(buildroot, buildconfig['overlays'])
+    rev_overlays = _ResolveOverlays(buildroot, buildconfig['rev_overlays'])
+    push_overlays = _ResolveOverlays(buildroot, buildconfig['push_overlays'])
+    # We cannot push to overlays that we don't rev.
+    assert set(push_overlays).issubset(set(rev_overlays))
+    # Either has to be a master or not have any push overlays.
+    assert buildconfig['master'] or not push_overlays
+
     board = buildconfig['board']
     old_binhost = None
 
-    _PreFlightRinse(buildroot, buildconfig['board'], tracking_branch, overlays)
+    _PreFlightRinse(buildroot, buildconfig['board'], tracking_branch,
+                    rev_overlays)
     chroot_path = os.path.join(buildroot, 'chroot')
     boardpath = os.path.join(chroot_path, 'build', board)
     if options.sync:
@@ -642,8 +650,7 @@ def main():
       RunCommand(['sudo', 'rm', '-rf', boardpath])
 
     # Check that all overlays can be found.
-    for path in overlays:
-      assert ':' not in path, 'Overlay must not contain colons: %s' % path
+    for path in rev_overlays:
       if not os.path.isdir(path):
         Die('Missing overlay: %s' % path)
 
@@ -659,7 +666,7 @@ def main():
                                                  options.chrome_rev)
     elif buildconfig['uprev']:
       _UprevPackages(buildroot, tracking_branch, revisionfile,
-                     buildconfig['board'], overlays)
+                     buildconfig['board'], rev_overlays)
 
     _EnableLocalAccount(buildroot)
     # Doesn't rebuild without acquiring more source.
@@ -681,7 +688,7 @@ def main():
         _RunSmokeSuite(buildroot, test_results_dir)
       finally:
         if not options.debug:
-          archive_full_path=os.path.join(options.gsutil_archive,
+          archive_full_path = os.path.join(options.gsutil_archive,
                                          str(options.buildnumber))
           _ArchiveTestResults(buildroot, buildconfig['board'],
                               test_results_dir=test_results_dir,
@@ -694,10 +701,10 @@ def main():
       if buildconfig['master']:
         # Master bot needs to check if the other slaves completed.
         if cbuildbot_comm.HaveSlavesCompleted(config):
-          _UploadPrebuilts(buildroot, board, buildconfig['overlays'],
+          _UploadPrebuilts(buildroot, board, buildconfig['rev_overlays'],
                            [new_binhost])
           _UprevPush(buildroot, tracking_branch, buildconfig['board'],
-                     overlays, options.debug)
+                     push_overlays, options.debug)
         else:
           Die('CBUILDBOT - One of the slaves has failed!!!')
 
diff --git a/bin/cbuildbot_config.py b/bin/cbuildbot_config.py
index 718cd36a70..ba3706e0f5 100644
--- a/bin/cbuildbot_config.py
+++ b/bin/cbuildbot_config.py
@@ -19,9 +19,12 @@ hostname -- Needed for 'important' slaves.  The hostname of the bot.  Should
             match hostname in slaves.cfg in buildbot checkout.
 unittests -- Runs unittests for packages.
 smoke_bvt -- Runs the test smoke suite in a qemu-based VM using KVM.
-overlays -- Select what overlays to look at. This can be 'public', 'private'
-            or 'both'. There should only be one master bot pushing changes to
-            each overlay per branch.
+rev_overlays -- Select what overlays to look at for revving. This can be
+                'public', 'private' or 'both'.
+push_overlays -- Select what overlays to push at. This should be a subset of
+                 rev_overlays for the particular builder.  Must be None if
+                 not a master.  There should only be one master bot pushing
+                 changes to each overlay per branch.
 """
 
 
@@ -33,7 +36,8 @@ config['default'] = {
   'important' : False,
   'unittests' : False,
   'smoke_bvt' : False,
-  'overlays': 'public',
+  'rev_overlays': 'public',
+  'push_overlays': None,
 }
 config['x86-generic-pre-flight-queue'] = {
   'board' : 'x86-generic',
@@ -43,7 +47,8 @@ config['x86-generic-pre-flight-queue'] = {
   'hostname' : 'chromeosbuild2',
   'unittests' : True,
   'smoke_bvt' : True,
-  'overlays': 'public',
+  'rev_overlays': 'public',
+  'push_overlays': 'public',
 }
 config['x86-mario-pre-flight-queue'] = {
   'board' : 'x86-mario',
@@ -52,7 +57,8 @@ config['x86-mario-pre-flight-queue'] = {
   'important' : False,
   'unittests' : True,
   'smoke_bvt' : True,
-  'overlays': 'private',
+  'rev_overlays': 'both',
+  'push_overlays': 'private',
 }
 config['x86-mario-pre-flight-branch'] = {
   'board' : 'x86-mario',
@@ -61,7 +67,8 @@ config['x86-mario-pre-flight-branch'] = {
   'important' : False,
   'unittests' : True,
   'smoke_bvt' : True,
-  'overlays': 'both',
+  'rev_overlays': 'both',
+  'push_overlays': 'both',
 }
 config['x86_agz_bin'] = {
   'board' : 'x86-agz',
@@ -70,7 +77,8 @@ config['x86_agz_bin'] = {
   'important' : False,
   'unittests' : True,
   'smoke_bvt' : True,
-  'overlays': 'private',
+  'rev_overlays': 'both',
+  'push_overlays': None,
 }
 config['x86_dogfood_bin'] = {
   'board' : 'x86-dogfood',
@@ -79,7 +87,8 @@ config['x86_dogfood_bin'] = {
   'important' : False,
   'unittests' : True,
   'smoke_bvt' : True,
-  'overlays': 'private',
+  'rev_overlays': 'both',
+  'push_overlays': None,
 }
 config['x86_pineview_bin'] = {
   'board' : 'x86-pineview',
@@ -87,7 +96,8 @@ config['x86_pineview_bin'] = {
   'master' : False,
   'important' : False,
   'unittests': True,
-  'overlays': 'public',
+  'rev_overlays': 'public',
+  'push_overlays': None,
 }
 config['arm_tegra2_bin'] = {
   'board' : 'tegra2',
@@ -95,7 +105,8 @@ config['arm_tegra2_bin'] = {
   'master' : False,
   'important' : False,
   'unittests' : False,
-  'overlays': 'public',
+  'rev_overlays': 'public',
+  'push_overlays': None,
 }
 config['arm_generic_bin'] = {
   'board' : 'arm-generic',
@@ -103,5 +114,6 @@ config['arm_generic_bin'] = {
   'master' : False,
   'important' : False,
   'unittests' : False,
-  'overlays': 'public',
+  'rev_overlays': 'public',
+  'push_overlays': None,
 }