diff --git a/fetch-negotiator.h b/fetch-negotiator.h
index e348905a1f..6ca422a064 100644
--- a/fetch-negotiator.h
+++ b/fetch-negotiator.h
@@ -47,6 +47,15 @@ struct fetch_negotiator {
 	 */
 	int (*ack)(struct fetch_negotiator *, struct commit *);
 
+	/*
+	 * Inform the negotiator that this commit has already been sent as
+	 * a "have" line outside of the negotiator's control. The negotiator
+	 * should avoid outputting it from next() and may use it to optimize
+	 * further negotiation (e.g., by treating it and its ancestors as
+	 * common).
+	 */
+	void (*have_sent)(struct fetch_negotiator *, struct commit *);
+
 	void (*release)(struct fetch_negotiator *);
 
 	/* internal use */
diff --git a/negotiator/default.c b/negotiator/default.c
index 116dedcf83..05ab616f39 100644
--- a/negotiator/default.c
+++ b/negotiator/default.c
@@ -175,6 +175,13 @@ static int ack(struct fetch_negotiator *n, struct commit *c)
 	return known_to_be_common;
 }
 
+static void have_sent(struct fetch_negotiator *n, struct commit *c)
+{
+	if (repo_parse_commit(the_repository, c))
+		return;
+	mark_common(n->data, c, 0, 0);
+}
+
 static void release(struct fetch_negotiator *n)
 {
 	clear_prio_queue(&((struct negotiation_state *)n->data)->rev_list);
@@ -188,6 +195,7 @@ void default_negotiator_init(struct fetch_negotiator *negotiator)
 	negotiator->add_tip = add_tip;
 	negotiator->next = next;
 	negotiator->ack = ack;
+	negotiator->have_sent = have_sent;
 	negotiator->release = release;
 	negotiator->data = CALLOC_ARRAY(ns, 1);
 	ns->rev_list.compare = compare_commits_by_commit_date;
diff --git a/negotiator/noop.c b/negotiator/noop.c
index 65e3c20008..edf1b456f3 100644
--- a/negotiator/noop.c
+++ b/negotiator/noop.c
@@ -29,6 +29,12 @@ static int ack(struct fetch_negotiator *n UNUSED, struct commit *c UNUSED)
 	return 0;
 }
 
+static void have_sent(struct fetch_negotiator *n UNUSED,
+		      struct commit *c UNUSED)
+{
+	/* nothing to do */
+}
+
 static void release(struct fetch_negotiator *n UNUSED)
 {
 	/* nothing to release */
@@ -40,6 +46,7 @@ void noop_negotiator_init(struct fetch_negotiator *negotiator)
 	negotiator->add_tip = add_tip;
 	negotiator->next = next;
 	negotiator->ack = ack;
+	negotiator->have_sent = have_sent;
 	negotiator->release = release;
 	negotiator->data = NULL;
 }
diff --git a/negotiator/skipping.c b/negotiator/skipping.c
index 0a272130fb..69472c58e1 100644
--- a/negotiator/skipping.c
+++ b/negotiator/skipping.c
@@ -243,6 +243,13 @@ static int ack(struct fetch_negotiator *n, struct commit *c)
 	return known_to_be_common;
 }
 
+static void have_sent(struct fetch_negotiator *n, struct commit *c)
+{
+	if (repo_parse_commit(the_repository, c))
+		return;
+	mark_common(n->data, c);
+}
+
 static void release(struct fetch_negotiator *n)
 {
 	struct data *data = n->data;
@@ -259,6 +266,7 @@ void skipping_negotiator_init(struct fetch_negotiator *negotiator)
 	negotiator->add_tip = add_tip;
 	negotiator->next = next;
 	negotiator->ack = ack;
+	negotiator->have_sent = have_sent;
 	negotiator->release = release;
 	negotiator->data = CALLOC_ARRAY(data, 1);
 	data->rev_list.compare = compare;