+	if (to_delete.nr)
+		ret = delete_branches(to_delete.nr, to_delete.v,
+				      FILTER_REFS_BRANCHES,
+				      DELETE_BRANCH_SKIP_UNMERGED |
+				      DELETE_BRANCH_NO_HEAD_FALLBACK |
+				      flags);
+
+	strvec_clear(&to_delete);
+	strset_clear(&deletable);
+	ref_array_clear(&candidates);
+	ref_filter_clear(&filter);
+	return ret;
+}
+
  static GIT_PATH_FUNC(edit_description, "EDIT_DESCRIPTION")
  
  static int edit_branch_description(const char *branch_name)

@@ -746,6 +862,7 @@ int cmd_branch(int argc,
  	/* possible actions */
  	int delete = 0, rename = 0, copy = 0, list = 0,
  	    unset_upstream = 0, show_current = 0, edit_description = 0;
+	int delete_merged = 0;
  	const char *new_upstream = NULL;
  	int noncreate_actions = 0;
  	/* possible options */

@@ -799,6 +916,8 @@ int cmd_branch(int argc,
  		OPT_BOOL(0, "create-reflog", &reflog, N_("create the branch's reflog")),
  		OPT_BOOL(0, "edit-description", &edit_description,
  			 N_("edit the description for the branch")),
+		OPT_BOOL(0, "delete-merged", &delete_merged,
+			N_("delete local branches whose upstream matches <branch> and are merged")),
  		OPT__FORCE(&force, N_("force creation, move/rename, deletion"), PARSE_OPT_NOCOMPLETE),
  		OPT_MERGED(&filter, N_("print only branches that are merged")),
  		OPT_NO_MERGED(&filter, N_("print only branches that are not merged")),

@@ -846,7 +965,8 @@ int cmd_branch(int argc,
  			     0);
  
  	if (!delete && !rename && !copy && !edit_description && !new_upstream &&
-	    !show_current && !unset_upstream && argc == 0)
+	    !show_current && !unset_upstream && !delete_merged &&
+	    argc == 0)
  		list = 1;
  
  	if (filter.with_commit || filter.no_commit ||

@@ -856,7 +976,7 @@ int cmd_branch(int argc,
  
  	noncreate_actions = !!delete + !!rename + !!copy + !!new_upstream +
  			    !!show_current + !!list + !!edit_description +
-			    !!unset_upstream;
+			    !!unset_upstream + !!delete_merged;
  	if (noncreate_actions > 1)
  		usage_with_options(builtin_branch_usage, options);
  

@@ -898,6 +1018,10 @@ int cmd_branch(int argc,
  				      (delete > 1 ? DELETE_BRANCH_FORCE : 0) |
  				      (quiet ? DELETE_BRANCH_QUIET : 0));
  		goto out;
+	} else if (delete_merged) {
+		ret = delete_merged_branches(argc, argv,
+					     quiet ? DELETE_BRANCH_QUIET : 0);
+		goto out;
  	} else if (show_current) {
  		print_current_branch_name();
  		ret = 0;

diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index 3104c555f6..1d372f95e8 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh

@@ -1839,4 +1839,155 @@ test_expect_success '--forked narrows a <pattern> argument' '
  	test_cmp expect actual
  '
  
+test_expect_success '--delete-merged: setup' '
+	git init -b main upstream &&
+	(
+		cd upstream &&
+		test_commit base &&
+		git checkout -b next &&
+		test_commit next-work &&
+		git checkout main
+	) &&
+	git init -b main other &&
+	test_commit -C other other-base &&
+	git init -b main fork
+'
+
+setup_repo_for_delete_merged () {
+	rm -rf repo &&
+	git clone upstream repo &&
+	(
+		cd repo &&
+		git remote add fork ../fork &&
+		git remote add other ../other &&
+		git config remote.pushDefault fork &&
+		git config push.default current &&
+		git fetch other
+	)
+}
+
+merged_branch () {
+	(
+		cd repo &&
+		git checkout -b "$1" "$2" &&
+		git commit --allow-empty -m "$1 work" &&
+		git push origin "$1:next" &&
+		git fetch origin &&
+		git branch --set-upstream-to="$2" "$1"
+	)
+}
+
+test_expect_success '--delete-merged deletes merged branches and spares the rest' '
+	test_when_finished "rm -rf repo" &&
+	setup_repo_for_delete_merged &&
+	merged_branch merged origin/next &&
+	(
+		cd repo &&
+		git checkout -b unmerged origin/next &&
+		git commit --allow-empty -m "unmerged work" &&
+		git branch --set-upstream-to=origin/next unmerged &&
+		git checkout -b tracks-other other/main &&
+		git branch --set-upstream-to=other/main tracks-other &&
+		git checkout --detach
+	) &&
+	sha=$(git -C repo rev-parse --short merged) &&
+
+	git -C repo branch --delete-merged origin/next >actual 2>&1 &&
+
+	echo "Deleted branch merged (was $sha)." >expect &&
+	test_cmp expect actual &&
+	git -C repo for-each-ref --format="%(refname:short)" refs/heads/ >actual &&
+	cat >expect <<-\EOF &&
+	main
+	tracks-other
+	unmerged
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success '--delete-merged deletes merged branches and spares protected ones' '
+	test_when_finished "rm -rf repo" &&
+	setup_repo_for_delete_merged &&
+	merged_branch on-next origin/next &&
+	merged_branch checked-out origin/next &&
+	merged_branch upstream-gone origin/next &&
+	(
+		cd repo &&
+		git checkout -b mainline main &&
+		git checkout -b on-local mainline &&
+		git branch --set-upstream-to=mainline on-local &&
+		git update-ref refs/remotes/origin/topic refs/remotes/origin/next &&
+		git branch --set-upstream-to=origin/topic upstream-gone &&
+		git update-ref -d refs/remotes/origin/topic &&
+		git branch --set-upstream-to=origin/main main &&
+		git config branch.main.pushRemote origin &&
+		git checkout -b tracks-other other/main &&
+		git branch --set-upstream-to=other/main tracks-other &&
+		git checkout checked-out
+	) &&
+
+	git -C repo branch --delete-merged origin/next mainline &&
+
+	git -C repo for-each-ref --format="%(refname:short)" refs/heads/ >actual &&
+	cat >expect <<-\EOF &&
+	checked-out
+	main
+	mainline
+	tracks-other
+	upstream-gone
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success '--delete-merged requires at least one <branch>' '
+	test_must_fail git -C forked branch --delete-merged 2>err &&
+	test_grep "requires at least one <branch>" err
+'
+
+test_expect_success '--delete-merged keeps a branch that is an upstream' '
+	test_when_finished "rm -rf repo" &&
+	setup_repo_for_delete_merged &&
+	merged_branch feature origin/next &&
+	(
+		cd repo &&
+		git checkout -b topic feature &&
+		git commit --allow-empty -m "topic work" &&
+		git branch --set-upstream-to=feature topic &&
+		git checkout --detach
+	) &&
+
+	git -C repo branch --delete-merged origin/next 2>err &&
+
+	test_must_be_empty err &&
+	git -C repo rev-parse --verify refs/heads/feature &&
+	git -C repo rev-parse --verify refs/heads/topic
+'
+
+test_expect_success '--delete-merged keeps a chain of upstreams of a kept branch' '
+	test_when_finished "rm -rf repo" &&
+	setup_repo_for_delete_merged &&
+	(
+		cd repo &&
+		git branch b3 origin/next &&
+		git branch --set-upstream-to=origin/next b3 &&
+		git branch b2 origin/next &&
+		git branch --set-upstream-to=b3 b2 &&
+		git checkout -b b1 b2 &&
+		git commit --allow-empty -m "b1 work" &&
+		git branch --set-upstream-to=b2 b1 &&
+		git checkout --detach
+	) &&
+
+	git -C repo branch --delete-merged origin/next &&
+
+	git -C repo for-each-ref --format="%(refname:short)" refs/heads/ >actual &&
+	cat >expect <<-\EOF &&
+	b1
+	b2
+	b3
+	main
+	EOF
+	test_cmp expect actual
+'
+
  test_done