diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 77826ea9dd..f8fb70c826 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -2009,6 +2009,20 @@ struct submodule_update_clone {
 	.max_jobs = 1, \
 }
 
+struct update_data {
+	const char *recursive_prefix;
+	const char *sm_path;
+	const char *displaypath;
+	struct object_id oid;
+	struct object_id suboid;
+	struct submodule_update_strategy update_strategy;
+	int depth;
+	unsigned int force: 1;
+	unsigned int quiet: 1;
+	unsigned int nofetch: 1;
+	unsigned int just_cloned: 1;
+};
+#define UPDATE_DATA_INIT { .update_strategy = SUBMODULE_UPDATE_STRATEGY_INIT }
 
 static void next_submodule_warn_missing(struct submodule_update_clone *suc,
 		struct strbuf *out, const char *displaypath)
@@ -2262,6 +2276,181 @@ static int git_update_clone_config(const char *var, const char *value,
 	return 0;
 }
 
+static int is_tip_reachable(const char *path, struct object_id *oid)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct strbuf rev = STRBUF_INIT;
+	char *hex = oid_to_hex(oid);
+
+	cp.git_cmd = 1;
+	cp.dir = xstrdup(path);
+	cp.no_stderr = 1;
+	strvec_pushl(&cp.args, "rev-list", "-n", "1", hex, "--not", "--all", NULL);
+
+	prepare_submodule_repo_env(&cp.env_array);
+
+	if (capture_command(&cp, &rev, GIT_MAX_HEXSZ + 1) || rev.len)
+		return 0;
+
+	return 1;
+}
+
+static int fetch_in_submodule(const char *module_path, int depth, int quiet, struct object_id *oid)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+
+	prepare_submodule_repo_env(&cp.env_array);
+	cp.git_cmd = 1;
+	cp.dir = xstrdup(module_path);
+
+	strvec_push(&cp.args, "fetch");
+	if (quiet)
+		strvec_push(&cp.args, "--quiet");
+	if (depth)
+		strvec_pushf(&cp.args, "--depth=%d", depth);
+	if (oid) {
+		char *hex = oid_to_hex(oid);
+		char *remote = get_default_remote();
+		strvec_pushl(&cp.args, remote, hex, NULL);
+	}
+
+	return run_command(&cp);
+}
+
+static int run_update_command(struct update_data *ud, int subforce)
+{
+	struct strvec args = STRVEC_INIT;
+	struct strvec child_env = STRVEC_INIT;
+	char *oid = oid_to_hex(&ud->oid);
+	int must_die_on_failure = 0;
+	int git_cmd;
+
+	switch (ud->update_strategy.type) {
+	case SM_UPDATE_CHECKOUT:
+		git_cmd = 1;
+		strvec_pushl(&args, "checkout", "-q", NULL);
+		if (subforce)
+			strvec_push(&args, "-f");
+		break;
+	case SM_UPDATE_REBASE:
+		git_cmd = 1;
+		strvec_push(&args, "rebase");
+		if (ud->quiet)
+			strvec_push(&args, "--quiet");
+		must_die_on_failure = 1;
+		break;
+	case SM_UPDATE_MERGE:
+		git_cmd = 1;
+		strvec_push(&args, "merge");
+		if (ud->quiet)
+			strvec_push(&args, "--quiet");
+		must_die_on_failure = 1;
+		break;
+	case SM_UPDATE_COMMAND:
+		git_cmd = 0;
+		strvec_push(&args, ud->update_strategy.command);
+		must_die_on_failure = 1;
+		break;
+	default:
+		BUG("unexpected update strategy type: %s",
+		    submodule_strategy_to_string(&ud->update_strategy));
+	}
+	strvec_push(&args, oid);
+
+	prepare_submodule_repo_env(&child_env);
+	if (run_command_v_opt_cd_env(args.v, git_cmd ? RUN_GIT_CMD : RUN_USING_SHELL,
+				     ud->sm_path, child_env.v)) {
+		switch (ud->update_strategy.type) {
+		case SM_UPDATE_CHECKOUT:
+			printf(_("Unable to checkout '%s' in submodule path '%s'"),
+			       oid, ud->displaypath);
+			break;
+		case SM_UPDATE_REBASE:
+			printf(_("Unable to rebase '%s' in submodule path '%s'"),
+			       oid, ud->displaypath);
+			break;
+		case SM_UPDATE_MERGE:
+			printf(_("Unable to merge '%s' in submodule path '%s'"),
+			       oid, ud->displaypath);
+			break;
+		case SM_UPDATE_COMMAND:
+			printf(_("Execution of '%s %s' failed in submodule path '%s'"),
+			       ud->update_strategy.command, oid, ud->displaypath);
+			break;
+		default:
+			BUG("unexpected update strategy type: %s",
+			    submodule_strategy_to_string(&ud->update_strategy));
+		}
+		/*
+		 * NEEDSWORK: We are currently printing to stdout with error
+		 * return so that the shell caller handles the error output
+		 * properly. Once we start handling the error messages within
+		 * C, we should use die() instead.
+		 */
+		if (must_die_on_failure)
+			return 2;
+		/*
+		 * This signifies to the caller in shell that the command
+		 * failed without dying
+		 */
+		return 1;
+	}
+
+	switch (ud->update_strategy.type) {
+	case SM_UPDATE_CHECKOUT:
+		printf(_("Submodule path '%s': checked out '%s'\n"),
+		       ud->displaypath, oid);
+		break;
+	case SM_UPDATE_REBASE:
+		printf(_("Submodule path '%s': rebased into '%s'\n"),
+		       ud->displaypath, oid);
+		break;
+	case SM_UPDATE_MERGE:
+		printf(_("Submodule path '%s': merged in '%s'\n"),
+		       ud->displaypath, oid);
+		break;
+	case SM_UPDATE_COMMAND:
+		printf(_("Submodule path '%s': '%s %s'\n"),
+		       ud->displaypath, ud->update_strategy.command, oid);
+		break;
+	default:
+		BUG("unexpected update strategy type: %s",
+		    submodule_strategy_to_string(&ud->update_strategy));
+	}
+
+	return 0;
+}
+
+static int do_run_update_procedure(struct update_data *ud)
+{
+	int subforce = is_null_oid(&ud->suboid) || ud->force;
+
+	if (!ud->nofetch) {
+		/*
+		 * Run fetch only if `oid` isn't present or it
+		 * is not reachable from a ref.
+		 */
+		if (!is_tip_reachable(ud->sm_path, &ud->oid) &&
+		    fetch_in_submodule(ud->sm_path, ud->depth, ud->quiet, NULL) &&
+		    !ud->quiet)
+			fprintf_ln(stderr,
+				   _("Unable to fetch in submodule path '%s'; "
+				     "trying to directly fetch %s:"),
+				   ud->displaypath, oid_to_hex(&ud->oid));
+		/*
+		 * Now we tried the usual fetch, but `oid` may
+		 * not be reachable from any of the refs.
+		 */
+		if (!is_tip_reachable(ud->sm_path, &ud->oid) &&
+		    fetch_in_submodule(ud->sm_path, ud->depth, ud->quiet, &ud->oid))
+			die(_("Fetched in submodule path '%s', but it did not "
+			      "contain %s. Direct fetching of that commit failed."),
+			    ud->displaypath, oid_to_hex(&ud->oid));
+	}
+
+	return run_update_command(ud, subforce);
+}
+
 static void update_submodule(struct update_clone_data *ucd)
 {
 	fprintf(stdout, "dummy %s %d\t%s\n",
@@ -2359,6 +2548,73 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 	return update_submodules(&suc);
 }
 
+static int run_update_procedure(int argc, const char **argv, const char *prefix)
+{
+	int force = 0, quiet = 0, nofetch = 0, just_cloned = 0;
+	char *prefixed_path, *update = NULL;
+	struct update_data update_data = UPDATE_DATA_INIT;
+
+	struct option options[] = {
+		OPT__QUIET(&quiet, N_("suppress output for update by rebase or merge")),
+		OPT__FORCE(&force, N_("force checkout updates"), 0),
+		OPT_BOOL('N', "no-fetch", &nofetch,
+			 N_("don't fetch new objects from the remote site")),
+		OPT_BOOL(0, "just-cloned", &just_cloned,
+			 N_("overrides update mode in case the repository is a fresh clone")),
+		OPT_INTEGER(0, "depth", &update_data.depth, N_("depth for shallow fetch")),
+		OPT_STRING(0, "prefix", &prefix,
+			   N_("path"),
+			   N_("path into the working tree")),
+		OPT_STRING(0, "update", &update,
+			   N_("string"),
+			   N_("rebase, merge, checkout or none")),
+		OPT_STRING(0, "recursive-prefix", &update_data.recursive_prefix, N_("path"),
+			   N_("path into the working tree, across nested "
+			      "submodule boundaries")),
+		OPT_CALLBACK_F(0, "oid", &update_data.oid, N_("sha1"),
+			       N_("SHA1 expected by superproject"), PARSE_OPT_NONEG,
+			       parse_opt_object_id),
+		OPT_CALLBACK_F(0, "suboid", &update_data.suboid, N_("subsha1"),
+			       N_("SHA1 of submodule's HEAD"), PARSE_OPT_NONEG,
+			       parse_opt_object_id),
+		OPT_END()
+	};
+
+	const char *const usage[] = {
+		N_("git submodule--helper run-update-procedure [<options>] <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	update_data.force = !!force;
+	update_data.quiet = !!quiet;
+	update_data.nofetch = !!nofetch;
+	update_data.just_cloned = !!just_cloned;
+	update_data.sm_path = argv[0];
+
+	if (update_data.recursive_prefix)
+		prefixed_path = xstrfmt("%s%s", update_data.recursive_prefix, update_data.sm_path);
+	else
+		prefixed_path = xstrdup(update_data.sm_path);
+
+	update_data.displaypath = get_submodule_displaypath(prefixed_path, prefix);
+
+	determine_submodule_update_strategy(the_repository, update_data.just_cloned,
+					    update_data.sm_path, update,
+					    &update_data.update_strategy);
+
+	free(prefixed_path);
+
+	if (!oideq(&update_data.oid, &update_data.suboid) || update_data.force)
+		return do_run_update_procedure(&update_data);
+
+	return 3;
+}
+
 static int resolve_relative_path(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf sb = STRBUF_INIT;
@@ -3098,6 +3354,7 @@ static struct cmd_struct commands[] = {
 	{"add", module_add, SUPPORT_SUPER_PREFIX},
 	{"update-module-mode", module_update_module_mode, 0},
 	{"update-clone", update_clone, 0},
+	{"run-update-procedure", run_update_procedure, 0},
 	{"ensure-core-worktree", ensure_core_worktree, 0},
 	{"relative-path", resolve_relative_path, 0},
 	{"resolve-relative-url-test", resolve_relative_url_test, 0},
diff --git a/git-submodule.sh b/git-submodule.sh
index 1070540525..27efdc5774 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -251,13 +251,6 @@ cmd_deinit()
 	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper deinit ${GIT_QUIET:+--quiet} ${force:+--force} ${deinit_all:+--all} -- "$@"
 }
 
-is_tip_reachable () (
-	sanitize_submodule_env &&
-	cd "$1" &&
-	rev=$(git rev-list -n 1 "$2" --not --all 2>/dev/null) &&
-	test -z "$rev"
-)
-
 # usage: fetch_in_submodule <module_path> [<depth>] [<sha1>]
 # Because arguments are positional, use an empty string to omit <depth>
 # but include <sha1>.
@@ -401,14 +394,13 @@ cmd_update()
 
 		git submodule--helper ensure-core-worktree "$sm_path" || exit 1
 
-		update_module=$(git submodule--helper update-module-mode $just_cloned "$sm_path" $update)
-
 		displaypath=$(git submodule--helper relative-path "$prefix$sm_path" "$wt_prefix")
 
 		if test $just_cloned -eq 1
 		then
 			subsha1=
 		else
+			just_cloned=
 			subsha1=$(sanitize_submodule_env; cd "$sm_path" &&
 				git rev-parse --verify HEAD) ||
 			die "fatal: $(eval_gettext "Unable to find current revision in submodule path '\$displaypath'")"
@@ -429,70 +421,38 @@ cmd_update()
 			die "fatal: $(eval_gettext "Unable to find current \${remote_name}/\${branch} revision in submodule path '\$sm_path'")"
 		fi
 
-		if test "$subsha1" != "$sha1" || test -n "$force"
-		then
-			subforce=$force
-			# If we don't already have a -f flag and the submodule has never been checked out
-			if test -z "$subsha1" && test -z "$force"
-			then
-				subforce="-f"
-			fi
+		out=$(git submodule--helper run-update-procedure \
+			  ${wt_prefix:+--prefix "$wt_prefix"} \
+			  ${GIT_QUIET:+--quiet} \
+			  ${force:+--force} \
+			  ${just_cloned:+--just-cloned} \
+			  ${nofetch:+--no-fetch} \
+			  ${depth:+"$depth"} \
+			  ${update:+--update "$update"} \
+			  ${prefix:+--recursive-prefix "$prefix"} \
+			  ${sha1:+--oid "$sha1"} \
+			  ${subsha1:+--suboid "$subsha1"} \
+			  "--" \
+			  "$sm_path")
 
-			if test -z "$nofetch"
-			then
-				# Run fetch only if $sha1 isn't present or it
-				# is not reachable from a ref.
-				is_tip_reachable "$sm_path" "$sha1" ||
-				fetch_in_submodule "$sm_path" $depth ||
-				say "$(eval_gettext "Unable to fetch in submodule path '\$displaypath'; trying to directly fetch \$sha1:")"
-
-				# Now we tried the usual fetch, but $sha1 may
-				# not be reachable from any of the refs
-				is_tip_reachable "$sm_path" "$sha1" ||
-				fetch_in_submodule "$sm_path" "$depth" "$sha1" ||
-				die "fatal: $(eval_gettext "Fetched in submodule path '\$displaypath', but it did not contain \$sha1. Direct fetching of that commit failed.")"
-			fi
-
-			must_die_on_failure=
-			case "$update_module" in
-			checkout)
-				command="git checkout $subforce -q"
-				die_msg="fatal: $(eval_gettext "Unable to checkout '\$sha1' in submodule path '\$displaypath'")"
-				say_msg="$(eval_gettext "Submodule path '\$displaypath': checked out '\$sha1'")"
-				;;
-			rebase)
-				command="git rebase ${GIT_QUIET:+--quiet}"
-				die_msg="fatal: $(eval_gettext "Unable to rebase '\$sha1' in submodule path '\$displaypath'")"
-				say_msg="$(eval_gettext "Submodule path '\$displaypath': rebased into '\$sha1'")"
-				must_die_on_failure=yes
-				;;
-			merge)
-				command="git merge ${GIT_QUIET:+--quiet}"
-				die_msg="fatal: $(eval_gettext "Unable to merge '\$sha1' in submodule path '\$displaypath'")"
-				say_msg="$(eval_gettext "Submodule path '\$displaypath': merged in '\$sha1'")"
-				must_die_on_failure=yes
-				;;
-			!*)
-				command="${update_module#!}"
-				die_msg="fatal: $(eval_gettext "Execution of '\$command \$sha1' failed in submodule path '\$displaypath'")"
-				say_msg="$(eval_gettext "Submodule path '\$displaypath': '\$command \$sha1'")"
-				must_die_on_failure=yes
-				;;
-			*)
-				die "fatal: $(eval_gettext "Invalid update mode '$update_module' for submodule path '$path'")"
-			esac
-
-			if (sanitize_submodule_env; cd "$sm_path" && $command "$sha1")
-			then
-				say "$say_msg"
-			elif test -n "$must_die_on_failure"
-			then
-				die_with_status 2 "$die_msg"
-			else
-				err="${err};$die_msg"
-				continue
-			fi
-		fi
+		# exit codes for run-update-procedure:
+		# 0: update was successful, say command output
+		# 1: update procedure failed, but should not die
+		# 2 or 128: subcommand died during execution
+		# 3: no update procedure was run
+		res="$?"
+		case $res in
+		0)
+			say "$out"
+			;;
+		1)
+			err="${err};fatal: $out"
+			continue
+			;;
+		2|128)
+			die_with_status $res "fatal: $out"
+			;;
+		esac
 
 		if test -n "$recursive"
 		then