diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -1249,15 +1249,33 @@
         pass
     return baseset(datarepr=('<max %r, %r>', subset, os))
 
-@predicate('merge()', safe=True)
+@predicate('merge(*withbranch)', safe=True)
 def merge(repo, subset, x):
-    """Changeset is a merge changeset.
+    """Changeset is a merge changeset
+
+    All merge revisions are returned by default. If one or more "withbranch"
+    names are provided only merges with those branches (i.e. whose
+    second parent belongs to one of those branches) will be returned.
     """
     # i18n: "merge" is a keyword
-    getargs(x, 0, 0, _("merge takes no arguments"))
+    args = getargsdict(x, 'merge', '*withbranch')
+    withbranches = []
+    if 'withbranch' in args:
+        for el in args['withbranch']:
+            # i18n: "withbranch" is a keyword
+            withbranches.append(getstring(el,
+                _('withbranch argument must be a string')))
     cl = repo.changelog
-    return subset.filter(lambda r: cl.parentrevs(r)[1] != -1,
-                         condrepr='<merge>')
+    if withbranches:
+        # basematch is a function that returns true when a revision
+        # is a merge and the second parent belongs to one of the
+        # selected "merge with branches"
+        matches = lambda r: (cl.parentrevs(r)[1] != -1
+                             and repo[r].p2().branch() in withbranches)
+    else:
+        # basematch is a function that returns true when a revision is a merge
+        matches = lambda r: cl.parentrevs(r)[1] != -1
+    return subset.filter(matches, condrepr='<merge>')
 
 @predicate('branchpoint()', safe=True)
 def branchpoint(repo, subset, x):