diff --git a/builtin/checkout.c b/builtin/checkout.c
index ada51fa70f..1b86d9c868 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -53,10 +53,10 @@ struct checkout_opts {
 static int post_checkout_hook(struct commit *old, struct commit *new,
 			      int changed)
 {
-	return run_hook(NULL, "post-checkout",
-			sha1_to_hex(old ? old->object.sha1 : null_sha1),
-			sha1_to_hex(new ? new->object.sha1 : null_sha1),
-			changed ? "1" : "0", NULL);
+	return run_hook_le(NULL, "post-checkout",
+			   sha1_to_hex(old ? old->object.sha1 : null_sha1),
+			   sha1_to_hex(new ? new->object.sha1 : null_sha1),
+			   changed ? "1" : "0", NULL);
 	/* "new" can be NULL when checking out from the index before
 	   a commit exists. */
 
diff --git a/builtin/clone.c b/builtin/clone.c
index 43e772ccdb..9b3c04d914 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -660,8 +660,8 @@ static int checkout(void)
 	    commit_locked_index(lock_file))
 		die(_("unable to write new index file"));
 
-	err |= run_hook(NULL, "post-checkout", sha1_to_hex(null_sha1),
-			sha1_to_hex(sha1), "1", NULL);
+	err |= run_hook_le(NULL, "post-checkout", sha1_to_hex(null_sha1),
+			   sha1_to_hex(sha1), "1", NULL);
 
 	if (!err && option_recursive)
 		err = run_command_v_opt(argv_submodule, RUN_GIT_CMD);
diff --git a/builtin/commit.c b/builtin/commit.c
index 38f34e7cd3..d9550c54d0 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -611,7 +611,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 	/* This checks and barfs if author is badly specified */
 	determine_author_info(author_ident);
 
-	if (!no_verify && run_hook(index_file, "pre-commit", NULL))
+	if (!no_verify && run_commit_hook(use_editor, index_file, "pre-commit", NULL))
 		return 0;
 
 	if (squash_message) {
@@ -873,8 +873,8 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		return 0;
 	}
 
-	if (run_hook(index_file, "prepare-commit-msg",
-		     git_path(commit_editmsg), hook_arg1, hook_arg2, NULL))
+	if (run_commit_hook(use_editor, index_file, "prepare-commit-msg",
+			    git_path(commit_editmsg), hook_arg1, hook_arg2, NULL))
 		return 0;
 
 	if (use_editor) {
@@ -890,7 +890,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 	}
 
 	if (!no_verify &&
-	    run_hook(index_file, "commit-msg", git_path(commit_editmsg), NULL)) {
+	    run_commit_hook(use_editor, index_file, "commit-msg", git_path(commit_editmsg), NULL)) {
 		return 0;
 	}
 
@@ -1074,8 +1074,6 @@ static int parse_and_validate_options(int argc, const char *argv[],
 		use_editor = 0;
 	if (0 <= edit_flag)
 		use_editor = edit_flag;
-	if (!use_editor)
-		setenv("GIT_EDITOR", ":", 1);
 
 	/* Sanity check options */
 	if (amend && !current_head)
@@ -1458,6 +1456,29 @@ static int run_rewrite_hook(const unsigned char *oldsha1,
 	return finish_command(&proc);
 }
 
+int run_commit_hook(int editor_is_used, const char *index_file, const char *name, ...)
+{
+	const char *hook_env[3] =  { NULL };
+	char index[PATH_MAX];
+	va_list args;
+	int ret;
+
+	snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
+	hook_env[0] = index;
+
+	/*
+	 * Let the hook know that no editor will be launched.
+	 */
+	if (!editor_is_used)
+		hook_env[1] = "GIT_EDITOR=:";
+
+	va_start(args, name);
+	ret = run_hook_ve(hook_env, name, args);
+	va_end(args);
+
+	return ret;
+}
+
 int cmd_commit(int argc, const char **argv, const char *prefix)
 {
 	static struct wt_status s;
@@ -1682,7 +1703,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		     "not exceeded, and then \"git reset HEAD\" to recover."));
 
 	rerere(0);
-	run_hook(get_index_file(), "post-commit", NULL);
+	run_commit_hook(use_editor, get_index_file(), "post-commit", NULL);
 	if (amend && !no_post_rewrite) {
 		struct notes_rewrite_cfg *cfg;
 		cfg = init_copy_notes_for_rewrite("amend");
diff --git a/builtin/gc.c b/builtin/gc.c
index 63d400bcb2..11cf295515 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -184,7 +184,7 @@ static int need_to_gc(void)
 	else if (!too_many_loose_objects())
 		return 0;
 
-	if (run_hook(NULL, "pre-auto-gc", NULL))
+	if (run_hook_le(NULL, "pre-auto-gc", NULL))
 		return 0;
 	return 1;
 }
diff --git a/builtin/merge.c b/builtin/merge.c
index f0cf1205fa..e15d0e145a 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -421,7 +421,7 @@ static void finish(struct commit *head_commit,
 	}
 
 	/* Run a post-merge hook */
-	run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
+	run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);
 
 	strbuf_release(&reflog_message);
 }
@@ -824,8 +824,8 @@ static void prepare_to_commit(struct commit_list *remoteheads)
 	if (0 < option_edit)
 		strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
 	write_merge_msg(&msg);
-	if (run_hook(get_index_file(), "prepare-commit-msg",
-		     git_path("MERGE_MSG"), "merge", NULL, NULL))
+	if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
+			    git_path("MERGE_MSG"), "merge", NULL))
 		abort_commit(remoteheads, NULL);
 	if (0 < option_edit) {
 		if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
diff --git a/commit.h b/commit.h
index 55631f191f..a9f177ba48 100644
--- a/commit.h
+++ b/commit.h
@@ -304,4 +304,7 @@ extern void check_commit_signature(const struct commit* commit, struct signature
 
 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused);
 
+LAST_ARG_MUST_BE_NULL
+extern int run_commit_hook(int editor_is_used, const char *index_file, const char *name, ...);
+
 #endif /* COMMIT_H */
diff --git a/run-command.c b/run-command.c
index 3914d9c511..75abc478c6 100644
--- a/run-command.c
+++ b/run-command.c
@@ -760,13 +760,11 @@ char *find_hook(const char *name)
 	return path;
 }
 
-int run_hook(const char *index_file, const char *name, ...)
+int run_hook_ve(const char *const *env, const char *name, va_list args)
 {
 	struct child_process hook;
 	struct argv_array argv = ARGV_ARRAY_INIT;
-	const char *p, *env[2];
-	char index[PATH_MAX];
-	va_list args;
+	const char *p;
 	int ret;
 
 	p = find_hook(name);
@@ -775,23 +773,45 @@ int run_hook(const char *index_file, const char *name, ...)
 
 	argv_array_push(&argv, p);
 
-	va_start(args, name);
 	while ((p = va_arg(args, const char *)))
 		argv_array_push(&argv, p);
-	va_end(args);
 
 	memset(&hook, 0, sizeof(hook));
 	hook.argv = argv.argv;
+	hook.env = env;
 	hook.no_stdin = 1;
 	hook.stdout_to_stderr = 1;
-	if (index_file) {
-		snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
-		env[0] = index;
-		env[1] = NULL;
-		hook.env = env;
-	}
 
 	ret = run_command(&hook);
 	argv_array_clear(&argv);
 	return ret;
 }
+
+int run_hook_le(const char *const *env, const char *name, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, name);
+	ret = run_hook_ve(env, name, args);
+	va_end(args);
+
+	return ret;
+}
+
+int run_hook_with_custom_index(const char *index_file, const char *name, ...)
+{
+	const char *hook_env[3] =  { NULL };
+	char index[PATH_MAX];
+	va_list args;
+	int ret;
+
+	snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
+	hook_env[0] = index;
+
+	va_start(args, name);
+	ret = run_hook_ve(hook_env, name, args);
+	va_end(args);
+
+	return ret;
+}
diff --git a/run-command.h b/run-command.h
index 6b985afd07..3653bfa6e1 100644
--- a/run-command.h
+++ b/run-command.h
@@ -47,7 +47,12 @@ int run_command(struct child_process *);
 
 extern char *find_hook(const char *name);
 LAST_ARG_MUST_BE_NULL
-extern int run_hook(const char *index_file, const char *name, ...);
+extern int run_hook_le(const char *const *env, const char *name, ...);
+extern int run_hook_ve(const char *const *env, const char *name, va_list args);
+
+LAST_ARG_MUST_BE_NULL
+__attribute__((deprecated))
+extern int run_hook_with_custom_index(const char *index_file, const char *name, ...);
 
 #define RUN_COMMAND_NO_STDIN 1
 #define RUN_GIT_CMD	     2	/*If this is to be git sub-command */
diff --git a/t/t7505-prepare-commit-msg-hook.sh b/t/t7505-prepare-commit-msg-hook.sh
index 357375151d..03dce09cfe 100755
--- a/t/t7505-prepare-commit-msg-hook.sh
+++ b/t/t7505-prepare-commit-msg-hook.sh
@@ -134,14 +134,26 @@ test_expect_success 'with hook (-c)' '
 
 test_expect_success 'with hook (merge)' '
 
-	head=`git rev-parse HEAD` &&
-	git checkout -b other HEAD@{1} &&
-	echo "more" >> file &&
+	test_when_finished "git checkout -f master" &&
+	git checkout -B other HEAD@{1} &&
+	echo "more" >>file &&
 	git add file &&
 	git commit -m other &&
 	git checkout - &&
-	git merge other &&
-	test "`git log -1 --pretty=format:%s`" = merge
+	git merge --no-ff other &&
+	test "`git log -1 --pretty=format:%s`" = "merge (no editor)"
+'
+
+test_expect_success 'with hook and editor (merge)' '
+
+	test_when_finished "git checkout -f master" &&
+	git checkout -B other HEAD@{1} &&
+	echo "more" >>file &&
+	git add file &&
+	git commit -m other &&
+	git checkout - &&
+	env GIT_EDITOR="\"\$FAKE_EDITOR\"" git merge --no-ff -e other &&
+	test "`git log -1 --pretty=format:%s`" = "merge"
 '
 
 cat > "$HOOK" <<'EOF'
@@ -151,34 +163,37 @@ EOF
 
 test_expect_success 'with failing hook' '
 
+	test_when_finished "git checkout -f master" &&
 	head=`git rev-parse HEAD` &&
 	echo "more" >> file &&
 	git add file &&
-	! GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit -c $head
+	test_must_fail env GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit -c $head
 
 '
 
 test_expect_success 'with failing hook (--no-verify)' '
 
+	test_when_finished "git checkout -f master" &&
 	head=`git rev-parse HEAD` &&
 	echo "more" >> file &&
 	git add file &&
-	! GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit --no-verify -c $head
+	test_must_fail env GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit --no-verify -c $head
 
 '
 
 test_expect_success 'with failing hook (merge)' '
 
+	test_when_finished "git checkout -f master" &&
 	git checkout -B other HEAD@{1} &&
 	echo "more" >> file &&
 	git add file &&
 	rm -f "$HOOK" &&
 	git commit -m other &&
-	write_script "$HOOK" <<-EOF
+	write_script "$HOOK" <<-EOF &&
 	exit 1
 	EOF
 	git checkout - &&
-	test_must_fail git merge other
+	test_must_fail git merge --no-ff other
 
 '
 
diff --git a/t/t7514-commit-patch.sh b/t/t7514-commit-patch.sh
new file mode 100755
index 0000000000..998a2103c7
--- /dev/null
+++ b/t/t7514-commit-patch.sh
@@ -0,0 +1,34 @@
+#!/bin/sh
+
+test_description='hunk edit with "commit -p -m"'
+. ./test-lib.sh
+
+if ! test_have_prereq PERL
+then
+	skip_all="skipping '$test_description' tests, perl not available"
+	test_done
+fi
+
+test_expect_success 'setup (initial)' '
+	echo line1 >file &&
+	git add file &&
+	git commit -m commit1
+'
+
+test_expect_success 'edit hunk "commit -p -m message"' '
+	test_when_finished "rm -f editor_was_started" &&
+	rm -f editor_was_started &&
+	echo more >>file &&
+	echo e | env GIT_EDITOR=": >editor_was_started" git commit -p -m commit2 file &&
+	test -r editor_was_started
+'
+
+test_expect_success 'edit hunk "commit --dry-run -p -m message"' '
+	test_when_finished "rm -f editor_was_started" &&
+	rm -f editor_was_started &&
+	echo more >>file &&
+	echo e | env GIT_EDITOR=": >editor_was_started" git commit -p -m commit3 file &&
+	test -r editor_was_started
+'
+
+test_done