diff --git a/builtin/checkout.c b/builtin/checkout.c
index 5df3837e31..624bfbad7c 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 3767478c6d..baf1fc0fff 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -612,7 +612,7 @@ 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) {
@@ -866,8 +866,8 @@ 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) {
@@ -883,7 +883,7 @@ 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;
 	}
 
@@ -1067,8 +1067,6 @@ 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)
@@ -1445,6 +1443,29 @@ 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;
@@ -1669,7 +1690,7 @@ 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 c19545d49e..7fa717a3b6 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -179,7 +179,7 @@ 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 e576a7fdc6..67f312d877 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);
 }
@@ -821,8 +821,8 @@ 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(1, 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 16d9c43513..8d97a5caa3 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..88460f9bfe 100644
--- a/run-command.h
+++ b/run-command.h
@@ -47,7 +47,11 @@ 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
+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/t7514-commit-patch.sh b/t/t7514-commit-patch.sh
index 41dd37af75..998a2103c7 100755
--- a/t/t7514-commit-patch.sh
+++ b/t/t7514-commit-patch.sh
@@ -15,7 +15,7 @@ test_expect_success 'setup (initial)' '
 	git commit -m commit1
 '
 
-test_expect_failure 'edit hunk "commit -p -m message"' '
+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 &&
@@ -23,7 +23,7 @@ test_expect_failure 'edit hunk "commit -p -m message"' '
 	test -r editor_was_started
 '
 
-test_expect_failure 'edit hunk "commit --dry-run -p -m message"' '
+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 &&