diff --git a/builtin/am.c b/builtin/am.c
index b6be1f1cb11e47..f4682b8e959f8d 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1613,7 +1613,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 	if (state->quiet)
 		o.verbosity = 0;
 
-	if (merge_recursive_generic(&o, &our_tree, &their_tree, 1, bases, &result)) {
+	if (merge_recursive_generic(&o, &our_tree, &their_tree, 1, bases, merge_recursive, &result)) {
 		repo_rerere(the_repository, state->allow_rerere_autoupdate);
 		free(their_tree_name);
 		return error(_("Failed to merge in the changes."));
diff --git a/builtin/merge-recursive.c b/builtin/merge-recursive.c
index a4bfd8fc51d6b2..58964676be9b35 100644
--- a/builtin/merge-recursive.c
+++ b/builtin/merge-recursive.c
@@ -81,7 +81,7 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 	if (o.verbosity >= 3)
 		printf(_("Merging %s with %s\n"), o.branch1, o.branch2);
 
-	failed = merge_recursive_generic(&o, &h1, &h2, bases_count, bases, &result);
+	failed = merge_recursive_generic(&o, &h1, &h2, bases_count, bases, merge_recursive, &result);
 
 	free(better1);
 	free(better2);
diff --git a/builtin/stash.c b/builtin/stash.c
index e3051e9c407f6e..5044720175602a 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -7,6 +7,7 @@
 #include "cache-tree.h"
 #include "unpack-trees.h"
 #include "merge-recursive.h"
+#include "merge-ort-wrappers.h"
 #include "strvec.h"
 #include "run-command.h"
 #include "dir.h"
@@ -554,7 +555,7 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 	bases[0] = &info->b_tree;
 
 	ret = merge_recursive_generic(&o, &c_tree, &info->w_tree, 1, bases,
-				      &result);
+				      merge_ort_recursive, &result);
 	if (ret) {
 		rerere(0);
 
@@ -1790,6 +1791,9 @@ int cmd_stash(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options, git_stash_usage,
 			     PARSE_OPT_KEEP_UNKNOWN | PARSE_OPT_KEEP_DASHDASH);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	index_file = get_index_file();
 	strbuf_addf(&stash_index_path, "%s.stash.%" PRIuMAX, index_file,
 		    (uintmax_t)pid);
diff --git a/merge-ort.c b/merge-ort.c
index 58038094836afa..d302f31753e754 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -4684,7 +4684,8 @@ void merge_incore_recursive(struct merge_options *opt,
 	trace2_region_enter("merge", "incore_recursive", opt->repo);
 
 	/* We set the ancestor label based on the merge_bases */
-	assert(opt->ancestor == NULL);
+	assert(opt->ancestor == NULL ||
+	       !strcmp(opt->ancestor, "constructed merge base"));
 
 	trace2_region_enter("merge", "merge_start", opt->repo);
 	merge_start(opt, result);
diff --git a/merge-recursive.c b/merge-recursive.c
index 593eab87910899..c108c69f385357 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -3799,6 +3799,7 @@ int merge_recursive_generic(struct merge_options *opt,
 			    const struct object_id *merge,
 			    int num_merge_bases,
 			    const struct object_id **merge_bases,
+			    recursive_merge_fn_t merge_fn,
 			    struct commit **result)
 {
 	int clean;
@@ -3822,8 +3823,7 @@ int merge_recursive_generic(struct merge_options *opt,
 	}
 
 	repo_hold_locked_index(opt->repo, &lock, LOCK_DIE_ON_ERROR);
-	clean = merge_recursive(opt, head_commit, next_commit, ca,
-				result);
+	clean = merge_fn(opt, head_commit, next_commit, ca, result);
 	if (clean < 0) {
 		rollback_lock_file(&lock);
 		return clean;
diff --git a/merge-recursive.h b/merge-recursive.h
index 0795a1d3ec1809..6436ddcdca9d49 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -51,6 +51,12 @@ struct merge_options {
 	struct merge_options_internal *priv;
 };
 
+typedef int (*recursive_merge_fn_t)(struct merge_options *opt,
+				    struct commit *h1,
+				    struct commit *h2,
+				    struct commit_list *merge_bases,
+				    struct commit **result);
+
 void init_merge_options(struct merge_options *opt, struct repository *repo);
 
 /* parse the option in s and update the relevant field of opt */
@@ -103,7 +109,7 @@ int merge_recursive(struct merge_options *opt,
 
 /*
  * merge_recursive_generic can operate on trees instead of commits, by
- * wrapping the trees into virtual commits, and calling merge_recursive().
+ * wrapping the trees into virtual commits, and calling the provided merge_fn.
  * It also writes out the in-memory index to disk if the merge is successful.
  *
  * Outputs:
@@ -118,6 +124,7 @@ int merge_recursive_generic(struct merge_options *opt,
 			    const struct object_id *merge,
 			    int num_merge_bases,
 			    const struct object_id **merge_bases,
+			    recursive_merge_fn_t merge_fn,
 			    struct commit **result);
 
 #endif
diff --git a/t/perf/p2000-sparse-operations.sh b/t/perf/p2000-sparse-operations.sh
index 5da8dd2c9baf66..4babe0b4ad4772 100755
--- a/t/perf/p2000-sparse-operations.sh
+++ b/t/perf/p2000-sparse-operations.sh
@@ -106,6 +106,7 @@ test_perf_on_all () {
 }
 
 test_perf_on_all git status
+test_perf_on_all 'git stash && git stash pop'
 test_perf_on_all git add -A
 test_perf_on_all git add .
 test_perf_on_all git commit -a -m A
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index 125d978112dee0..9b2259a06c54e6 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -1258,6 +1258,19 @@ test_expect_success 'sparse-index is not expanded' '
 	echo >>sparse-index/untracked.txt &&
 	ensure_not_expanded add . &&
 
+	echo >>sparse-index/a &&
+	ensure_not_expanded stash &&
+	ensure_not_expanded stash list &&
+	ensure_not_expanded stash show stash@{0} &&
+	ensure_not_expanded stash apply stash@{0} &&
+	ensure_not_expanded stash drop stash@{0} &&
+
+	ensure_not_expanded stash create &&
+	oid=$(git -C sparse-index stash create) &&
+	ensure_not_expanded stash store -m "test" $oid &&
+	ensure_not_expanded reset --hard &&
+	ensure_not_expanded stash pop &&
+
 	ensure_not_expanded checkout-index -f a &&
 	ensure_not_expanded checkout-index -f --all &&
 	for ref in update-deep update-folder1 update-folder2 update-deep