diff --git a/docs/manifest-format.md b/docs/manifest-format.md
index 6e67108..0d26296 100644
--- a/docs/manifest-format.md
+++ b/docs/manifest-format.md
@@ -66,6 +66,7 @@
   <!ATTLIST submanifest revision       CDATA #IMPLIED>
   <!ATTLIST submanifest path           CDATA #IMPLIED>
   <!ATTLIST submanifest groups         CDATA #IMPLIED>
+  <!ATTLIST submanifest default-groups CDATA #IMPLIED>
 
   <!ELEMENT project (annotation*,
                      project*,
@@ -302,6 +303,9 @@
 all projects in submanifests carry all parent submanifest groups.
 Same syntax as the corresponding element of `project`.
 
+Attribute `default-groups`: The list of manifest groups to sync if no
+`--groups=` parameter was specified at init.  When that list is empty, use this
+list instead of "default" as the list of groups to sync.
 
 ### Element project
 
diff --git a/manifest_xml.py b/manifest_xml.py
index dbab974..3c43295 100644
--- a/manifest_xml.py
+++ b/manifest_xml.py
@@ -214,6 +214,7 @@
     revision: a string, the commitish.
     manifestName: a string, the submanifest file name.
     groups: a list of strings, the groups to add to all projects in the submanifest.
+    default_groups: a list of strings, the default groups to sync.
     path: a string, the relative path for the submanifest checkout.
     parent: an XmlManifest, the parent manifest.
     annotations: (derived) a list of annotations.
@@ -226,6 +227,7 @@
                revision=None,
                manifestName=None,
                groups=None,
+               default_groups=None,
                path=None,
                parent=None):
     self.name = name
@@ -234,6 +236,7 @@
     self.revision = revision
     self.manifestName = manifestName
     self.groups = groups
+    self.default_groups = default_groups
     self.path = path
     self.parent = parent
     self.annotations = []
@@ -250,7 +253,8 @@
         os.path.join(parent.path_prefix, self.relpath), MANIFEST_FILE_NAME)
     rc = self.repo_client = RepoClient(
         parent.repodir, linkFile, parent_groups=','.join(groups) or '',
-        submanifest_path=self.relpath, outer_client=outer_client)
+        submanifest_path=self.relpath, outer_client=outer_client,
+        default_groups=default_groups)
 
     self.present = os.path.exists(manifestFile)
 
@@ -264,6 +268,7 @@
         self.revision == other.revision and
         self.manifestName == other.manifestName and
         self.groups == other.groups and
+        self.default_groups == other.default_groups and
         self.path == other.path and
         sorted(self.annotations) == sorted(other.annotations))
 
@@ -284,6 +289,7 @@
     revision = self.revision or self.name
     path = self.path or revision.split('/')[-1]
     groups = self.groups or []
+    default_groups = self.default_groups or []
 
     return SubmanifestSpec(self.name, manifestUrl, manifestName, revision, path,
                            groups)
@@ -300,6 +306,10 @@
       return ','.join(self.groups)
     return ''
 
+  def GetDefaultGroupsStr(self):
+    """Returns the `default-groups` given for this submanifest."""
+    return ','.join(self.default_groups or [])
+
   def AddAnnotation(self, name, value, keep):
     """Add annotations to the submanifest."""
     self.annotations.append(Annotation(name, value, keep))
@@ -327,7 +337,8 @@
   """manages the repo configuration file"""
 
   def __init__(self, repodir, manifest_file, local_manifests=None,
-               outer_client=None, parent_groups='', submanifest_path=''):
+               outer_client=None, parent_groups='', submanifest_path='',
+               default_groups=None):
     """Initialize.
 
     Args:
@@ -340,6 +351,7 @@
       outer_client: RepoClient of the outertree.
       parent_groups: a string, the groups to apply to this projects.
       submanifest_path: The submanifest root relative to the repo root.
+      default_groups: a string, the default manifest groups to use.
     """
     # TODO(vapier): Move this out of this class.
     self.globalConfig = GitConfig.ForUser()
@@ -358,6 +370,7 @@
     self.local_manifests = local_manifests
     self._load_local_manifests = True
     self.parent_groups = parent_groups
+    self.default_groups = default_groups
 
     if outer_client and self.isGitcClient:
       raise ManifestParseError('Multi-manifest is incompatible with `gitc-init`')
@@ -472,6 +485,8 @@
       e.setAttribute('path', r.path)
     if r.groups:
       e.setAttribute('groups', r.GetGroupsStr())
+    if r.default_groups:
+      e.setAttribute('default-groups', r.GetDefaultGroupsStr())
 
     for a in r.annotations:
       if a.keep == 'true':
@@ -967,16 +982,21 @@
                          worktree=os.path.join(subdir, 'manifests'))
     return mp
 
-  def GetDefaultGroupsStr(self):
-    """Returns the default group string for the platform."""
-    return 'default,platform-' + platform.system().lower()
+  def GetDefaultGroupsStr(self, with_platform=True):
+    """Returns the default group string to use.
+
+    Args:
+      with_platform: a boolean, whether to include the group for the
+                     underlying platform.
+    """
+    groups = ','.join(self.default_groups or ['default'])
+    if with_platform:
+      groups += f',platform-{platform.system().lower()}'
+    return groups
 
   def GetGroupsStr(self):
     """Returns the manifest group string that should be synced."""
-    groups = self.manifestProject.manifest_groups
-    if not groups:
-      groups = self.GetDefaultGroupsStr()
-    return groups
+    return self.manifestProject.manifest_groups or self.GetDefaultGroupsStr()
 
   def Unload(self):
     """Unload the manifest.
@@ -1491,6 +1511,7 @@
     if node.hasAttribute('groups'):
       groups = node.getAttribute('groups')
     groups = self._ParseList(groups)
+    default_groups = self._ParseList(node.getAttribute('default-groups'))
     path = node.getAttribute('path')
     if path == '':
       path = None
@@ -1511,7 +1532,7 @@
             '<submanifest> invalid "path": %s: %s' % (path, msg))
 
     submanifest = _XmlSubmanifest(name, remote, project, revision, manifestName,
-                                  groups, path, self)
+                                  groups, default_groups, path, self)
 
     for n in node.childNodes:
       if n.nodeName == 'annotation':
diff --git a/project.py b/project.py
index 7afd6a7..2641c44 100644
--- a/project.py
+++ b/project.py
@@ -715,7 +715,8 @@
        The special manifest group "default" will match any project that
        does not have the special project group "notdefault"
     """
-    expanded_manifest_groups = manifest_groups or ['default']
+    default_groups = self.manifest.default_groups or ['default']
+    expanded_manifest_groups = manifest_groups or default_groups
     expanded_project_groups = ['all'] + (self.groups or [])
     if 'notdefault' not in expanded_project_groups:
       expanded_project_groups += ['default']
@@ -3496,7 +3497,7 @@
     """
     assert _kwargs_only == (), 'Sync only accepts keyword arguments.'
 
-    groups = groups or 'default'
+    groups = groups or self.manifest.GetDefaultGroupsStr(with_platform=False)
     platform = platform or 'auto'
     git_event_log = git_event_log or EventLog()
     if outer_manifest and self.manifest.is_submanifest:
diff --git a/subcmds/info.py b/subcmds/info.py
index 4bedf9d..baa4c5b 100644
--- a/subcmds/info.py
+++ b/subcmds/info.py
@@ -65,8 +65,7 @@
       self.manifest = self.manifest.outer_client
     manifestConfig = self.manifest.manifestProject.config
     mergeBranch = manifestConfig.GetBranch("default").merge
-    manifestGroups = (manifestConfig.GetString('manifest.groups')
-                      or 'all,-notdefault')
+    manifestGroups = self.manifest.GetGroupsStr()
 
     self.heading("Manifest branch: ")
     if self.manifest.default.revisionExpr: