diff --git a/mercurial/manifest.py b/mercurial/manifest.py
--- a/mercurial/manifest.py
+++ b/mercurial/manifest.py
@@ -1155,6 +1155,22 @@ class treemanifest(object):
                 subp1, subp2 = subp2, subp1
             writesubtree(subm, subp1, subp2)
 
+    def walksubtrees(self, matcher=None):
+        """Returns an iterator of the subtrees of this manifest, including this
+        manifest itself.
+
+        If `matcher` is provided, it only returns subtrees that match.
+        """
+        if matcher and not matcher.visitdir(self._dir[:-1] or '.'):
+            return
+        if not matcher or matcher(self._dir[:-1]):
+            yield self
+
+        self._load()
+        for d, subm in self._dirs.iteritems():
+            for subtree in subm.walksubtrees(matcher=matcher):
+                yield subtree
+
 class manifestrevlog(revlog.revlog):
     '''A revlog that stores manifest texts. This is responsible for caching the
     full-text manifest contents.
diff --git a/tests/test-manifest.py b/tests/test-manifest.py
--- a/tests/test-manifest.py
+++ b/tests/test-manifest.py
@@ -467,5 +467,21 @@ class testtreemanifest(unittest.TestCase
     def parsemanifest(self, text):
         return manifestmod.treemanifest('', text)
 
+    def testWalkSubtrees(self):
+        m = self.parsemanifest(A_DEEPER_MANIFEST)
+
+        dirs = [s._dir for s in m.walksubtrees()]
+        self.assertEqual(
+            sorted(['', 'a/', 'a/c/', 'a/d/', 'a/b/', 'a/b/c/', 'a/b/d/']),
+            sorted(dirs)
+        )
+
+        match = matchmod.match('/', '', ['path:a/b/'])
+        dirs = [s._dir for s in m.walksubtrees(matcher=match)]
+        self.assertEqual(
+            sorted(['a/b/', 'a/b/c/', 'a/b/d/']),
+            sorted(dirs)
+        )
+
 if __name__ == '__main__':
     silenttestrunner.main(__name__)