diff --git a/Documentation/git-multi-pack-index.txt b/Documentation/git-multi-pack-index.txt
index 009c989ef8..27f83932e4 100644
--- a/Documentation/git-multi-pack-index.txt
+++ b/Documentation/git-multi-pack-index.txt
@@ -49,6 +49,21 @@ write::
 	--stdin-packs::
 		Write a multi-pack index containing only the set of
 		line-delimited pack index basenames provided over stdin.
+
+	--refs-snapshot=<path>::
+		With `--bitmap`, optionally specify a file which
+		contains a "refs snapshot" taken prior to repacking.
++
+A reference snapshot is composed of line-delimited OIDs corresponding to
+the reference tips, usually taken by `git repack` prior to generating a
+new pack. A line may optionally start with a `+` character to indicate
+that the reference which corresponds to that OID is "preferred" (see
+linkgit:git-config[1]'s `pack.preferBitmapTips`.)
++
+The file given at `<path>` is expected to be readable, and can contain
+duplicates. (If a given OID is given more than once, it is marked as
+preferred if at least one instance of it begins with the special `+`
+marker).
 --
 
 verify::
diff --git a/builtin/multi-pack-index.c b/builtin/multi-pack-index.c
index 047647b5f2..4b827a07c0 100644
--- a/builtin/multi-pack-index.c
+++ b/builtin/multi-pack-index.c
@@ -7,7 +7,8 @@
 #include "object-store.h"
 
 #define BUILTIN_MIDX_WRITE_USAGE \
-	N_("git multi-pack-index [<options>] write [--preferred-pack=<pack>]")
+	N_("git multi-pack-index [<options>] write [--preferred-pack=<pack>]" \
+	   "[--refs-snapshot=<path>]")
 
 #define BUILTIN_MIDX_VERIFY_USAGE \
 	N_("git multi-pack-index [<options>] verify")
@@ -45,6 +46,7 @@ static char const * const builtin_multi_pack_index_usage[] = {
 static struct opts_multi_pack_index {
 	const char *object_dir;
 	const char *preferred_pack;
+	const char *refs_snapshot;
 	unsigned long batch_size;
 	unsigned flags;
 	int stdin_packs;
@@ -83,6 +85,8 @@ static int cmd_multi_pack_index_write(int argc, const char **argv)
 			MIDX_WRITE_BITMAP | MIDX_WRITE_REV_INDEX),
 		OPT_BOOL(0, "stdin-packs", &opts.stdin_packs,
 			 N_("write multi-pack index containing only given indexes")),
+		OPT_FILENAME(0, "refs-snapshot", &opts.refs_snapshot,
+			     N_("refs snapshot for selecting bitmap commits")),
 		OPT_END(),
 	};
 
@@ -106,7 +110,8 @@ static int cmd_multi_pack_index_write(int argc, const char **argv)
 		read_packs_from_stdin(&packs);
 
 		ret = write_midx_file_only(opts.object_dir, &packs,
-					   opts.preferred_pack, opts.flags);
+					   opts.preferred_pack,
+					   opts.refs_snapshot, opts.flags);
 
 		string_list_clear(&packs, 0);
 
@@ -114,7 +119,7 @@ static int cmd_multi_pack_index_write(int argc, const char **argv)
 
 	}
 	return write_midx_file(opts.object_dir, opts.preferred_pack,
-			       opts.flags);
+			       opts.refs_snapshot, opts.flags);
 }
 
 static int cmd_multi_pack_index_verify(int argc, const char **argv)
diff --git a/builtin/repack.c b/builtin/repack.c
index 82ab668272..27158a897b 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -733,7 +733,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		unsigned flags = 0;
 		if (git_env_bool(GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP, 0))
 			flags |= MIDX_WRITE_BITMAP | MIDX_WRITE_REV_INDEX;
-		write_midx_file(get_object_directory(), NULL, flags);
+		write_midx_file(get_object_directory(), NULL, NULL, flags);
 	}
 
 	string_list_clear(&names, 0);
diff --git a/midx.c b/midx.c
index 5533361997..18a4f25aa3 100644
--- a/midx.c
+++ b/midx.c
@@ -983,7 +983,43 @@ static void bitmap_show_commit(struct commit *commit, void *_data)
 	data->commits[data->commits_nr++] = commit;
 }
 
+static int read_refs_snapshot(const char *refs_snapshot,
+			      struct rev_info *revs)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct object_id oid;
+	FILE *f = xfopen(refs_snapshot, "r");
+
+	while (strbuf_getline(&buf, f) != EOF) {
+		struct object *object;
+		int preferred = 0;
+		char *hex = buf.buf;
+		const char *end = NULL;
+
+		if (buf.len && *buf.buf == '+') {
+			preferred = 1;
+			hex = &buf.buf[1];
+		}
+
+		if (parse_oid_hex(hex, &oid, &end) < 0)
+			die(_("could not parse line: %s"), buf.buf);
+		if (*end)
+			die(_("malformed line: %s"), buf.buf);
+
+		object = parse_object_or_die(&oid, NULL);
+		if (preferred)
+			object->flags |= NEEDS_BITMAP;
+
+		add_pending_object(revs, object, "");
+	}
+
+	fclose(f);
+	strbuf_release(&buf);
+	return 0;
+}
+
 static struct commit **find_commits_for_midx_bitmap(uint32_t *indexed_commits_nr_p,
+						    const char *refs_snapshot,
 						    struct write_midx_context *ctx)
 {
 	struct rev_info revs;
@@ -992,8 +1028,12 @@ static struct commit **find_commits_for_midx_bitmap(uint32_t *indexed_commits_nr
 	cb.ctx = ctx;
 
 	repo_init_revisions(the_repository, &revs, NULL);
-	setup_revisions(0, NULL, &revs, NULL);
-	for_each_ref(add_ref_to_pending, &revs);
+	if (refs_snapshot) {
+		read_refs_snapshot(refs_snapshot, &revs);
+	} else {
+		setup_revisions(0, NULL, &revs, NULL);
+		for_each_ref(add_ref_to_pending, &revs);
+	}
 
 	/*
 	 * Skipping promisor objects here is intentional, since it only excludes
@@ -1022,6 +1062,7 @@ static struct commit **find_commits_for_midx_bitmap(uint32_t *indexed_commits_nr
 
 static int write_midx_bitmap(char *midx_name, unsigned char *midx_hash,
 			     struct write_midx_context *ctx,
+			     const char *refs_snapshot,
 			     unsigned flags)
 {
 	struct packing_data pdata;
@@ -1033,7 +1074,7 @@ static int write_midx_bitmap(char *midx_name, unsigned char *midx_hash,
 
 	prepare_midx_packing_data(&pdata, ctx);
 
-	commits = find_commits_for_midx_bitmap(&commits_nr, ctx);
+	commits = find_commits_for_midx_bitmap(&commits_nr, refs_snapshot, ctx);
 
 	/*
 	 * Build the MIDX-order index based on pdata.objects (which is already
@@ -1081,6 +1122,7 @@ static int write_midx_internal(const char *object_dir,
 			       struct string_list *packs_to_include,
 			       struct string_list *packs_to_drop,
 			       const char *preferred_pack_name,
+			       const char *refs_snapshot,
 			       unsigned flags)
 {
 	char *midx_name;
@@ -1374,7 +1416,8 @@ static int write_midx_internal(const char *object_dir,
 	if (flags & MIDX_WRITE_REV_INDEX)
 		write_midx_reverse_index(midx_name, midx_hash, &ctx);
 	if (flags & MIDX_WRITE_BITMAP) {
-		if (write_midx_bitmap(midx_name, midx_hash, &ctx, flags) < 0) {
+		if (write_midx_bitmap(midx_name, midx_hash, &ctx,
+				      refs_snapshot, flags) < 0) {
 			error(_("could not write multi-pack bitmap"));
 			result = 1;
 			goto cleanup;
@@ -1409,19 +1452,21 @@ cleanup:
 
 int write_midx_file(const char *object_dir,
 		    const char *preferred_pack_name,
+		    const char *refs_snapshot,
 		    unsigned flags)
 {
 	return write_midx_internal(object_dir, NULL, NULL, preferred_pack_name,
-				   flags);
+				   refs_snapshot, flags);
 }
 
 int write_midx_file_only(const char *object_dir,
 			 struct string_list *packs_to_include,
 			 const char *preferred_pack_name,
+			 const char *refs_snapshot,
 			 unsigned flags)
 {
 	return write_midx_internal(object_dir, packs_to_include, NULL,
-				   preferred_pack_name, flags);
+				   preferred_pack_name, refs_snapshot, flags);
 }
 
 struct clear_midx_data {
@@ -1701,7 +1746,7 @@ int expire_midx_packs(struct repository *r, const char *object_dir, unsigned fla
 	free(count);
 
 	if (packs_to_drop.nr) {
-		result = write_midx_internal(object_dir, NULL, &packs_to_drop, NULL, flags);
+		result = write_midx_internal(object_dir, NULL, &packs_to_drop, NULL, NULL, flags);
 		m = NULL;
 	}
 
@@ -1892,7 +1937,7 @@ int midx_repack(struct repository *r, const char *object_dir, size_t batch_size,
 		goto cleanup;
 	}
 
-	result = write_midx_internal(object_dir, NULL, NULL, NULL, flags);
+	result = write_midx_internal(object_dir, NULL, NULL, NULL, NULL, flags);
 	m = NULL;
 
 cleanup:
diff --git a/midx.h b/midx.h
index 3545e327ea..11ff094a8c 100644
--- a/midx.h
+++ b/midx.h
@@ -62,14 +62,18 @@ int fill_midx_entry(struct repository *r, const struct object_id *oid, struct pa
 int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name);
 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local);
 
-int write_midx_file(const char *object_dir, const char *preferred_pack_name, unsigned flags);
 /*
  * Variant of write_midx_file which writes a MIDX containing only the packs
  * specified in packs_to_include.
  */
+int write_midx_file(const char *object_dir,
+		    const char *preferred_pack_name,
+		    const char *refs_snapshot,
+		    unsigned flags);
 int write_midx_file_only(const char *object_dir,
 			 struct string_list *packs_to_include,
 			 const char *preferred_pack_name,
+			 const char *refs_snapshot,
 			 unsigned flags);
 void clear_midx_file(struct repository *r);
 int verify_midx_file(struct repository *r, const char *object_dir, unsigned flags);
diff --git a/t/t5326-multi-pack-bitmaps.sh b/t/t5326-multi-pack-bitmaps.sh
index 4ad7c2c969..069dab3e17 100755
--- a/t/t5326-multi-pack-bitmaps.sh
+++ b/t/t5326-multi-pack-bitmaps.sh
@@ -283,4 +283,86 @@ test_expect_success 'pack.preferBitmapTips' '
 	)
 '
 
+test_expect_success 'writing a bitmap with --refs-snapshot' '
+	git init repo &&
+	test_when_finished "rm -fr repo" &&
+	(
+		cd repo &&
+
+		test_commit one &&
+		test_commit two &&
+
+		git rev-parse one >snapshot &&
+
+		git repack -ad &&
+
+		# First, write a MIDX which see both refs/tags/one and
+		# refs/tags/two (causing both of those commits to receive
+		# bitmaps).
+		git multi-pack-index write --bitmap &&
+
+		test_path_is_file $midx &&
+		test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
+
+		test-tool bitmap list-commits | sort >bitmaps &&
+		grep "$(git rev-parse one)" bitmaps &&
+		grep "$(git rev-parse two)" bitmaps &&
+
+		rm -fr $midx-$(midx_checksum $objdir).bitmap &&
+		rm -fr $midx-$(midx_checksum $objdir).rev &&
+		rm -fr $midx &&
+
+		# Then again, but with a refs snapshot which only sees
+		# refs/tags/one.
+		git multi-pack-index write --bitmap --refs-snapshot=snapshot &&
+
+		test_path_is_file $midx &&
+		test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
+
+		test-tool bitmap list-commits | sort >bitmaps &&
+		grep "$(git rev-parse one)" bitmaps &&
+		! grep "$(git rev-parse two)" bitmaps
+	)
+'
+
+test_expect_success 'write a bitmap with --refs-snapshot (preferred tips)' '
+	git init repo &&
+	test_when_finished "rm -fr repo" &&
+	(
+		cd repo &&
+
+		test_commit_bulk --message="%s" 103 &&
+
+		git log --format="%H" >commits.raw &&
+		sort <commits.raw >commits &&
+
+		git log --format="create refs/tags/%s %H" HEAD >refs &&
+		git update-ref --stdin <refs &&
+
+		git multi-pack-index write --bitmap &&
+		test_path_is_file $midx &&
+		test_path_is_file $midx-$(midx_checksum $objdir).bitmap &&
+
+		test-tool bitmap list-commits | sort >bitmaps &&
+		comm -13 bitmaps commits >before &&
+		test_line_count = 1 before &&
+
+		(
+			grep -vf before commits.raw &&
+			# mark missing commits as preferred
+			sed "s/^/+/" before
+		) >snapshot &&
+
+		rm -fr $midx-$(midx_checksum $objdir).bitmap &&
+		rm -fr $midx-$(midx_checksum $objdir).rev &&
+		rm -fr $midx &&
+
+		git multi-pack-index write --bitmap --refs-snapshot=snapshot &&
+		test-tool bitmap list-commits | sort >bitmaps &&
+		comm -13 bitmaps commits >after &&
+
+		! test_cmp before after
+	)
+'
+
 test_done