diff --git a/merge-ort.c b/merge-ort.c
index 7e624fcd36..ad94b30a76 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -1230,6 +1230,18 @@ static int collect_merge_info_callback(int n,
 	return mask;
 }
 
+static void resolve_trivial_directory_merge(struct conflict_info *ci, int side)
+{
+	VERIFY_CI(ci);
+	assert((side == 1 && ci->match_mask == 5) ||
+	       (side == 2 && ci->match_mask == 3));
+	oidcpy(&ci->merged.result.oid, &ci->stages[side].oid);
+	ci->merged.result.mode = ci->stages[side].mode;
+	ci->merged.is_null = is_null_oid(&ci->stages[side].oid);
+	ci->match_mask = 0;
+	ci->merged.clean = 1; /* (ci->filemask == 0); */
+}
+
 static int handle_deferred_entries(struct merge_options *opt,
 				   struct traverse_info *info)
 {
@@ -1239,9 +1251,72 @@ static int handle_deferred_entries(struct merge_options *opt,
 	int side, ret = 0;
 
 	for (side = MERGE_SIDE1; side <= MERGE_SIDE2; side++) {
-		renames->deferred[side].trivial_merges_okay = 0;
-		strintmap_for_each_entry(&renames->deferred[side].possible_trivial_merges,
-					 &iter, entry) {
+		unsigned optimization_okay = 1;
+		struct strintmap copy;
+
+		/* Loop over the set of paths we need to know rename info for */
+		strset_for_each_entry(&renames->relevant_sources[side],
+				      &iter, entry) {
+			char *rename_target, *dir, *dir_marker;
+			struct strmap_entry *e;
+
+			/*
+			 * If we don't know delete/rename info for this path,
+			 * then we need to recurse into all trees to get all
+			 * adds to make sure we have it.
+			 */
+			if (strset_contains(&renames->cached_irrelevant[side],
+					    entry->key))
+				continue;
+			e = strmap_get_entry(&renames->cached_pairs[side],
+					     entry->key);
+			if (!e) {
+				optimization_okay = 0;
+				break;
+			}
+
+			/* If this is a delete, we have enough info already */
+			rename_target = e->value;
+			if (!rename_target)
+				continue;
+
+			/* If we already walked the rename target, we're good */
+			if (strmap_contains(&opt->priv->paths, rename_target))
+				continue;
+
+			/*
+			 * Otherwise, we need to get a list of directories that
+			 * will need to be recursed into to get this
+			 * rename_target.
+			 */
+			dir = xstrdup(rename_target);
+			while ((dir_marker = strrchr(dir, '/'))) {
+				*dir_marker = '\0';
+				if (strset_contains(&renames->deferred[side].target_dirs,
+						    dir))
+					break;
+				strset_add(&renames->deferred[side].target_dirs,
+					   dir);
+			}
+			free(dir);
+		}
+		renames->deferred[side].trivial_merges_okay = optimization_okay;
+		/*
+		 * We need to recurse into any directories in
+		 * possible_trivial_merges[side] found in target_dirs[side].
+		 * But when we recurse, we may need to queue up some of the
+		 * subdirectories for possible_trivial_merges[side].  Since
+		 * we can't safely iterate through a hashmap while also adding
+		 * entries, move the entries into 'copy', iterate over 'copy',
+		 * and then we'll also iterate anything added into
+		 * possible_trivial_merges[side] once this loop is done.
+		 */
+		copy = renames->deferred[side].possible_trivial_merges;
+		strintmap_init_with_options(&renames->deferred[side].possible_trivial_merges,
+					    0,
+					    NULL,
+					    0);
+		strintmap_for_each_entry(&copy, &iter, entry) {
 			const char *path = entry->key;
 			unsigned dir_rename_mask = (intptr_t)entry->value;
 			struct conflict_info *ci;
@@ -1254,6 +1329,13 @@ static int handle_deferred_entries(struct merge_options *opt,
 			VERIFY_CI(ci);
 			dirmask = ci->dirmask;
 
+			if (optimization_okay &&
+			    !strset_contains(&renames->deferred[side].target_dirs,
+					     path)) {
+				resolve_trivial_directory_merge(ci, side);
+				continue;
+			}
+
 			info->name = path;
 			info->namelen = strlen(path);
 			info->pathlen = info->namelen + 1;
@@ -1289,6 +1371,20 @@ static int handle_deferred_entries(struct merge_options *opt,
 			if (ret < 0)
 				return ret;
 		}
+		strintmap_clear(&copy);
+		strintmap_for_each_entry(&renames->deferred[side].possible_trivial_merges,
+					 &iter, entry) {
+			const char *path = entry->key;
+			struct conflict_info *ci;
+
+			ci = strmap_get(&opt->priv->paths, path);
+			VERIFY_CI(ci);
+
+			assert(renames->deferred[side].trivial_merges_okay &&
+			       !strset_contains(&renames->deferred[side].target_dirs,
+						path));
+			resolve_trivial_directory_merge(ci, side);
+		}
 	}
 	return ret;
 }