commit.c |   42 +++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 41 insertions(+), 1 deletions(-)

diff --git a/commit.c b/commit.c
index ac337c7d7dc1..0d33c33a6520 100644
--- a/commit.c
+++ b/commit.c
@@ -737,16 +737,56 @@ struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 	return get_merge_bases_many(one, 1, &two, cleanup);
 }
 
+#define VISITED (1 << 16)
+
+static int is_recursive_descendant(struct commit *commit, struct commit *target)
+{
+	int slop = 5;
+	parse_commit(target);
+	for (;;) {
+		struct commit_list *parents;
+		if (commit == target)
+			return 1;
+		if (commit->object.flags & VISITED)
+			return 0;
+		commit->object.flags |= VISITED;
+		parse_commit(commit);
+		if (commit->date + 5*24*60*60 < target->date) {
+			if (--slop <= 0)
+				return 0;
+		} else
+			slop = 5;
+		parents = commit->parents;
+		if (!parents)
+			return 0;
+		commit = parents->item;
+		parents = parents->next;
+		while (parents) {
+			if (is_recursive_descendant(parents->item, target))
+				return 1;
+			parents = parents->next;
+		}
+	}
+}
+
+static int is_descendant(struct commit *commit, struct commit *target)
+{
+	int ret = is_recursive_descendant(commit, target);
+	clear_commit_marks(commit, VISITED);
+	return ret;
+}
+
 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 {
 	if (!with_commit)
 		return 1;
+
 	while (with_commit) {
 		struct commit *other;
 
 		other = with_commit->item;
 		with_commit = with_commit->next;
-		if (in_merge_bases(other, &commit, 1))
+		if (is_descendant(commit, other))
 			return 1;
 	}
 	return 0;