diff --git a/Documentation/config/gc.txt b/Documentation/config/gc.txt
index ca47eb2008..466466d6cc 100644
--- a/Documentation/config/gc.txt
+++ b/Documentation/config/gc.txt
@@ -145,6 +145,22 @@ Multiple hooks are supported, but all must exit successfully, else the
 operation (either generating a cruft pack or unpacking unreachable
 objects) will be halted.
 
+gc.repackFilter::
+	When repacking, use the specified filter to move certain
+	objects into a separate packfile.  See the
+	`--filter=<filter-spec>` option of linkgit:git-repack[1].
+
+gc.repackFilterTo::
+	When repacking and using a filter, see `gc.repackFilter`, the
+	specified location will be used to create the packfile
+	containing the filtered out objects. **WARNING:** The
+	specified location should be accessible, using for example the
+	Git alternates mechanism, otherwise the repo could be
+	considered corrupt by Git as it migh not be able to access the
+	objects in that packfile. See the `--filter-to=<dir>` option
+	of linkgit:git-repack[1] and the `objects/info/alternates`
+	section of linkgit:gitrepository-layout[5].
+
 gc.rerereResolved::
 	Records of conflicted merge you resolved earlier are
 	kept for this many days when 'git rerere gc' is run.
diff --git a/Documentation/git-pack-objects.txt b/Documentation/git-pack-objects.txt
index dea7eacb0f..e32404c6aa 100644
--- a/Documentation/git-pack-objects.txt
+++ b/Documentation/git-pack-objects.txt
@@ -296,8 +296,8 @@ So does `git bundle` (see linkgit:git-bundle[1]) when it creates a bundle.
 	nevertheless.
 
 --filter=<filter-spec>::
-	Requires `--stdout`.  Omits certain objects (usually blobs) from
-	the resulting packfile.  See linkgit:git-rev-list[1] for valid
+	Omits certain objects (usually blobs) from the resulting
+	packfile.  See linkgit:git-rev-list[1] for valid
 	`<filter-spec>` forms.
 
 --no-filter::
diff --git a/Documentation/git-repack.txt b/Documentation/git-repack.txt
index 4017157949..8545a32667 100644
--- a/Documentation/git-repack.txt
+++ b/Documentation/git-repack.txt
@@ -143,6 +143,29 @@ depth is 4095.
 	a larger and slower repository; see the discussion in
 	`pack.packSizeLimit`.
 
+--filter=<filter-spec>::
+	Remove objects matching the filter specification from the
+	resulting packfile and put them into a separate packfile. Note
+	that objects used in the working directory are not filtered
+	out. So for the split to fully work, it's best to perform it
+	in a bare repo and to use the `-a` and `-d` options along with
+	this option.  Also `--no-write-bitmap-index` (or the
+	`repack.writebitmaps` config option set to `false`) should be
+	used otherwise writing bitmap index will fail, as it supposes
+	a single packfile containing all the objects. See
+	linkgit:git-rev-list[1] for valid `<filter-spec>` forms.
+
+--filter-to=<dir>::
+	Write the pack containing filtered out objects to the
+	directory `<dir>`. Only useful with `--filter`. This can be
+	used for putting the pack on a separate object directory that
+	is accessed through the Git alternates mechanism. **WARNING:**
+	If the packfile containing the filtered out objects is not
+	accessible, the repo can become corrupt as it might not be
+	possible to access the objects in that packfile. See the
+	`objects` and `objects/info/alternates` sections of
+	linkgit:gitrepository-layout[5].
+
 -b::
 --write-bitmap-index::
 	Write a reachability bitmap index as part of the repack. This
diff --git a/Makefile b/Makefile
index 795ebc67e8..9c6a2f125f 100644
--- a/Makefile
+++ b/Makefile
@@ -800,6 +800,7 @@ TEST_BUILTINS_OBJS += test-dump-untracked-cache.o
 TEST_BUILTINS_OBJS += test-env-helper.o
 TEST_BUILTINS_OBJS += test-example-decorate.o
 TEST_BUILTINS_OBJS += test-fast-rebase.o
+TEST_BUILTINS_OBJS += test-find-pack.o
 TEST_BUILTINS_OBJS += test-fsmonitor-client.o
 TEST_BUILTINS_OBJS += test-genrandom.o
 TEST_BUILTINS_OBJS += test-genzeros.o
diff --git a/builtin/gc.c b/builtin/gc.c
index 00192ae5d3..68ca8d45bf 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -61,6 +61,8 @@ static timestamp_t gc_log_expire_time;
 static const char *gc_log_expire = "1.day.ago";
 static const char *prune_expire = "2.weeks.ago";
 static const char *prune_worktrees_expire = "3.months.ago";
+static char *repack_filter;
+static char *repack_filter_to;
 static unsigned long big_pack_threshold;
 static unsigned long max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE;
 
@@ -170,6 +172,9 @@ static void gc_config(void)
 	git_config_get_ulong("gc.bigpackthreshold", &big_pack_threshold);
 	git_config_get_ulong("pack.deltacachesize", &max_delta_cache_size);
 
+	git_config_get_string("gc.repackfilter", &repack_filter);
+	git_config_get_string("gc.repackfilterto", &repack_filter_to);
+
 	git_config(git_default_config, NULL);
 }
 
@@ -355,6 +360,11 @@ static void add_repack_all_option(struct string_list *keep_pack)
 
 	if (keep_pack)
 		for_each_string_list(keep_pack, keep_one_pack, NULL);
+
+	if (repack_filter && *repack_filter)
+		strvec_pushf(&repack, "--filter=%s", repack_filter);
+	if (repack_filter_to && *repack_filter_to)
+		strvec_pushf(&repack, "--filter-to=%s", repack_filter_to);
 }
 
 static void add_repack_incremental_option(void)
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 6eb9756836..89a8b5a976 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -4402,12 +4402,8 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	if (!rev_list_all || !rev_list_reflog || !rev_list_index)
 		unpack_unreachable_expiration = 0;
 
-	if (filter_options.choice) {
-		if (!pack_to_stdout)
-			die(_("cannot use --filter without --stdout"));
-		if (stdin_packs)
-			die(_("cannot use --filter with --stdin-packs"));
-	}
+	if (stdin_packs && filter_options.choice)
+		die(_("cannot use --filter with --stdin-packs"));
 
 	if (stdin_packs && use_internal_rev_list)
 		die(_("cannot use internal rev list with --stdin-packs"));
diff --git a/builtin/repack.c b/builtin/repack.c
index 529e13120d..db9277081d 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -21,6 +21,7 @@
 #include "pack.h"
 #include "pack-bitmap.h"
 #include "refs.h"
+#include "list-objects-filter-options.h"
 
 #define ALL_INTO_ONE 1
 #define LOOSEN_UNREACHABLE 2
@@ -56,6 +57,7 @@ struct pack_objects_args {
 	int no_reuse_object;
 	int quiet;
 	int local;
+	struct list_objects_filter_options filter_options;
 };
 
 static int repack_config(const char *var, const char *value,
@@ -806,6 +808,86 @@ static void remove_redundant_bitmaps(struct string_list *include,
 	strbuf_release(&path);
 }
 
+static int finish_pack_objects_cmd(struct child_process *cmd,
+				   struct string_list *names,
+				   int local)
+{
+	FILE *out;
+	struct strbuf line = STRBUF_INIT;
+
+	out = xfdopen(cmd->out, "r");
+	while (strbuf_getline_lf(&line, out) != EOF) {
+		struct string_list_item *item;
+
+		if (line.len != the_hash_algo->hexsz)
+			die(_("repack: Expecting full hex object ID lines only "
+			      "from pack-objects."));
+		/*
+		 * Avoid putting packs written outside of the repository in the
+		 * list of names.
+		 */
+		if (local) {
+			item = string_list_append(names, line.buf);
+			item->util = populate_pack_exts(line.buf);
+		}
+	}
+	fclose(out);
+
+	strbuf_release(&line);
+
+	return finish_command(cmd);
+}
+
+static int write_filtered_pack(const struct pack_objects_args *args,
+			       const char *destination,
+			       const char *pack_prefix,
+			       struct existing_packs *existing,
+			       struct string_list *names)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct string_list_item *item;
+	FILE *in;
+	int ret;
+	const char *caret;
+	const char *scratch;
+	int local = skip_prefix(destination, packdir, &scratch);
+
+	prepare_pack_objects(&cmd, args, destination);
+
+	strvec_push(&cmd.args, "--stdin-packs");
+
+	if (!pack_kept_objects)
+		strvec_push(&cmd.args, "--honor-pack-keep");
+	for_each_string_list_item(item, &existing->kept_packs)
+		strvec_pushf(&cmd.args, "--keep-pack=%s", item->string);
+
+	cmd.in = -1;
+
+	ret = start_command(&cmd);
+	if (ret)
+		return ret;
+
+	/*
+	 * Here 'names' contains only the pack(s) that were just
+	 * written, which is exactly the packs we want to keep. Also
+	 * 'existing_kept_packs' already contains the packs in
+	 * 'keep_pack_list'.
+	 */
+	in = xfdopen(cmd.in, "w");
+	for_each_string_list_item(item, names)
+		fprintf(in, "^%s-%s.pack\n", pack_prefix, item->string);
+	for_each_string_list_item(item, &existing->non_kept_packs)
+		fprintf(in, "%s.pack\n", item->string);
+	for_each_string_list_item(item, &existing->cruft_packs)
+		fprintf(in, "%s.pack\n", item->string);
+	caret = pack_kept_objects ? "" : "^";
+	for_each_string_list_item(item, &existing->kept_packs)
+		fprintf(in, "%s%s.pack\n", caret, item->string);
+	fclose(in);
+
+	return finish_pack_objects_cmd(&cmd, names, local);
+}
+
 static int write_cruft_pack(const struct pack_objects_args *args,
 			    const char *destination,
 			    const char *pack_prefix,
@@ -814,9 +896,8 @@ static int write_cruft_pack(const struct pack_objects_args *args,
 			    struct existing_packs *existing)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
-	struct strbuf line = STRBUF_INIT;
 	struct string_list_item *item;
-	FILE *in, *out;
+	FILE *in;
 	int ret;
 	const char *scratch;
 	int local = skip_prefix(destination, packdir, &scratch);
@@ -861,27 +942,18 @@ static int write_cruft_pack(const struct pack_objects_args *args,
 		fprintf(in, "%s.pack\n", item->string);
 	fclose(in);
 
-	out = xfdopen(cmd.out, "r");
-	while (strbuf_getline_lf(&line, out) != EOF) {
-		struct string_list_item *item;
+	return finish_pack_objects_cmd(&cmd, names, local);
+}
 
-		if (line.len != the_hash_algo->hexsz)
-			die(_("repack: Expecting full hex object ID lines only "
-			      "from pack-objects."));
-		/*
-		 * avoid putting packs written outside of the repository in the
-		 * list of names
-		 */
-		if (local) {
-			item = string_list_append(names, line.buf);
-			item->util = populate_pack_exts(line.buf);
-		}
-	}
-	fclose(out);
-
-	strbuf_release(&line);
-
-	return finish_command(&cmd);
+static const char *find_pack_prefix(const char *packdir, const char *packtmp)
+{
+	const char *pack_prefix;
+	if (!skip_prefix(packtmp, packdir, &pack_prefix))
+		die(_("pack prefix %s does not begin with objdir %s"),
+		    packtmp, packdir);
+	if (*pack_prefix == '/')
+		pack_prefix++;
+	return pack_prefix;
 }
 
 int cmd_repack(int argc, const char **argv, const char *prefix)
@@ -891,10 +963,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	struct string_list names = STRING_LIST_INIT_DUP;
 	struct existing_packs existing = EXISTING_PACKS_INIT;
 	struct pack_geometry geometry = { 0 };
-	struct strbuf line = STRBUF_INIT;
 	struct tempfile *refs_snapshot = NULL;
 	int i, ext, ret;
-	FILE *out;
 	int show_progress;
 
 	/* variables to be filled by option parsing */
@@ -907,6 +977,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	int write_midx = 0;
 	const char *cruft_expiration = NULL;
 	const char *expire_to = NULL;
+	const char *filter_to = NULL;
 
 	struct option builtin_repack_options[] = {
 		OPT_BIT('a', NULL, &pack_everything,
@@ -948,6 +1019,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 				N_("limits the maximum number of threads")),
 		OPT_STRING(0, "max-pack-size", &po_args.max_pack_size, N_("bytes"),
 				N_("maximum size of each packfile")),
+		OPT_PARSE_LIST_OBJECTS_FILTER(&po_args.filter_options),
 		OPT_BOOL(0, "pack-kept-objects", &pack_kept_objects,
 				N_("repack objects in packs marked with .keep")),
 		OPT_STRING_LIST(0, "keep-pack", &keep_pack_list, N_("name"),
@@ -958,9 +1030,13 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 			   N_("write a multi-pack index of the resulting packs")),
 		OPT_STRING(0, "expire-to", &expire_to, N_("dir"),
 			   N_("pack prefix to store a pack containing pruned objects")),
+		OPT_STRING(0, "filter-to", &filter_to, N_("dir"),
+			   N_("pack prefix to store a pack containing filtered out objects")),
 		OPT_END()
 	};
 
+	list_objects_filter_init(&po_args.filter_options);
+
 	git_config(repack_config, &cruft_po_args);
 
 	argc = parse_options(argc, argv, prefix, builtin_repack_options,
@@ -1101,6 +1177,12 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		strvec_push(&cmd.args, "--incremental");
 	}
 
+	if (po_args.filter_options.choice)
+		strvec_pushf(&cmd.args, "--filter=%s",
+			     expand_list_objects_filter_spec(&po_args.filter_options));
+	else if (filter_to)
+		die(_("option '%s' can only be used along with '%s'"), "--filter-to", "--filter");
+
 	if (geometry.split_factor)
 		cmd.in = -1;
 	else
@@ -1124,18 +1206,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		fclose(in);
 	}
 
-	out = xfdopen(cmd.out, "r");
-	while (strbuf_getline_lf(&line, out) != EOF) {
-		struct string_list_item *item;
-
-		if (line.len != the_hash_algo->hexsz)
-			die(_("repack: Expecting full hex object ID lines only from pack-objects."));
-		item = string_list_append(&names, line.buf);
-		item->util = populate_pack_exts(item->string);
-	}
-	strbuf_release(&line);
-	fclose(out);
-	ret = finish_command(&cmd);
+	ret = finish_pack_objects_cmd(&cmd, &names, 1);
 	if (ret)
 		goto cleanup;
 
@@ -1143,12 +1214,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		printf_ln(_("Nothing new to pack."));
 
 	if (pack_everything & PACK_CRUFT) {
-		const char *pack_prefix;
-		if (!skip_prefix(packtmp, packdir, &pack_prefix))
-			die(_("pack prefix %s does not begin with objdir %s"),
-			    packtmp, packdir);
-		if (*pack_prefix == '/')
-			pack_prefix++;
+		const char *pack_prefix = find_pack_prefix(packdir, packtmp);
 
 		if (!cruft_po_args.window)
 			cruft_po_args.window = po_args.window;
@@ -1203,6 +1269,19 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		}
 	}
 
+	if (po_args.filter_options.choice) {
+		if (!filter_to)
+			filter_to = packtmp;
+
+		ret = write_filtered_pack(&po_args,
+					  filter_to,
+					  find_pack_prefix(packdir, packtmp),
+					  &existing,
+					  &names);
+		if (ret)
+			goto cleanup;
+	}
+
 	string_list_sort(&names);
 
 	close_object_store(the_repository->objects);
@@ -1295,6 +1374,7 @@ cleanup:
 	string_list_clear(&names, 1);
 	existing_packs_release(&existing);
 	free_pack_geometry(&geometry);
+	list_objects_filter_release(&po_args.filter_options);
 
 	return ret;
 }
diff --git a/pack-bitmap-write.c b/pack-bitmap-write.c
index f6757c3cbf..f4ecdf8b0e 100644
--- a/pack-bitmap-write.c
+++ b/pack-bitmap-write.c
@@ -413,15 +413,19 @@ static int fill_bitmap_commit(struct bb_commit *ent,
 
 		if (old_bitmap && mapping) {
 			struct ewah_bitmap *old = bitmap_for_commit(old_bitmap, c);
+			struct bitmap *remapped = bitmap_new();
 			/*
 			 * If this commit has an old bitmap, then translate that
 			 * bitmap and add its bits to this one. No need to walk
 			 * parents or the tree for this commit.
 			 */
-			if (old && !rebuild_bitmap(mapping, old, ent->bitmap)) {
+			if (old && !rebuild_bitmap(mapping, old, remapped)) {
+				bitmap_or(ent->bitmap, remapped);
+				bitmap_free(remapped);
 				reused_bitmaps_nr++;
 				continue;
 			}
+			bitmap_free(remapped);
 		}
 
 		/*
diff --git a/t/helper/test-find-pack.c b/t/helper/test-find-pack.c
new file mode 100644
index 0000000000..e8bd793e58
--- /dev/null
+++ b/t/helper/test-find-pack.c
@@ -0,0 +1,50 @@
+#include "test-tool.h"
+#include "object-name.h"
+#include "object-store.h"
+#include "packfile.h"
+#include "parse-options.h"
+#include "setup.h"
+
+/*
+ * Display the path(s), one per line, of the packfile(s) containing
+ * the given object.
+ *
+ * If '--check-count <n>' is passed, then error out if the number of
+ * packfiles containing the object is not <n>.
+ */
+
+static const char *find_pack_usage[] = {
+	"test-tool find-pack [--check-count <n>] <object>",
+	NULL
+};
+
+int cmd__find_pack(int argc, const char **argv)
+{
+	struct object_id oid;
+	struct packed_git *p;
+	int count = -1, actual_count = 0;
+	const char *prefix = setup_git_directory();
+
+	struct option options[] = {
+		OPT_INTEGER('c', "check-count", &count, "expected number of packs"),
+		OPT_END(),
+	};
+
+	argc = parse_options(argc, argv, prefix, options, find_pack_usage, 0);
+	if (argc != 1)
+		usage(find_pack_usage[0]);
+
+	if (repo_get_oid(the_repository, argv[0], &oid))
+		die("cannot parse %s as an object name", argv[0]);
+
+	for (p = get_all_packs(the_repository); p; p = p->next)
+		if (find_pack_entry_one(oid.hash, p)) {
+			printf("%s\n", p->pack_name);
+			actual_count++;
+		}
+
+	if (count > -1 && count != actual_count)
+		die("bad packfile count %d instead of %d", actual_count, count);
+
+	return 0;
+}
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index 621ac3dd10..9010ac6de7 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -31,6 +31,7 @@ static struct test_cmd cmds[] = {
 	{ "env-helper", cmd__env_helper },
 	{ "example-decorate", cmd__example_decorate },
 	{ "fast-rebase", cmd__fast_rebase },
+	{ "find-pack", cmd__find_pack },
 	{ "fsmonitor-client", cmd__fsmonitor_client },
 	{ "genrandom", cmd__genrandom },
 	{ "genzeros", cmd__genzeros },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index a641c3a81d..f134f96b97 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -25,6 +25,7 @@ int cmd__dump_reftable(int argc, const char **argv);
 int cmd__env_helper(int argc, const char **argv);
 int cmd__example_decorate(int argc, const char **argv);
 int cmd__fast_rebase(int argc, const char **argv);
+int cmd__find_pack(int argc, const char **argv);
 int cmd__fsmonitor_client(int argc, const char **argv);
 int cmd__genrandom(int argc, const char **argv);
 int cmd__genzeros(int argc, const char **argv);
diff --git a/t/t0081-find-pack.sh b/t/t0081-find-pack.sh
new file mode 100755
index 0000000000..67b11216a3
--- /dev/null
+++ b/t/t0081-find-pack.sh
@@ -0,0 +1,82 @@
+#!/bin/sh
+
+test_description='test `test-tool find-pack`'
+
+TEST_PASSES_SANITIZE_LEAK=true
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit one &&
+	test_commit two &&
+	test_commit three &&
+	test_commit four &&
+	test_commit five
+'
+
+test_expect_success 'repack everything into a single packfile' '
+	git repack -a -d --no-write-bitmap-index &&
+
+	head_commit_pack=$(test-tool find-pack HEAD) &&
+	head_tree_pack=$(test-tool find-pack HEAD^{tree}) &&
+	one_pack=$(test-tool find-pack HEAD:one.t) &&
+	three_pack=$(test-tool find-pack HEAD:three.t) &&
+	old_commit_pack=$(test-tool find-pack HEAD~4) &&
+
+	test-tool find-pack --check-count 1 HEAD &&
+	test-tool find-pack --check-count=1 HEAD^{tree} &&
+	! test-tool find-pack --check-count=0 HEAD:one.t &&
+	! test-tool find-pack -c 2 HEAD:one.t &&
+	test-tool find-pack -c 1 HEAD:three.t &&
+
+	# Packfile exists at the right path
+	case "$head_commit_pack" in
+		".git/objects/pack/pack-"*".pack") true ;;
+		*) false ;;
+	esac &&
+	test -f "$head_commit_pack" &&
+
+	# Everything is in the same pack
+	test "$head_commit_pack" = "$head_tree_pack" &&
+	test "$head_commit_pack" = "$one_pack" &&
+	test "$head_commit_pack" = "$three_pack" &&
+	test "$head_commit_pack" = "$old_commit_pack"
+'
+
+test_expect_success 'add more packfiles' '
+	git rev-parse HEAD^{tree} HEAD:two.t HEAD:four.t >objects &&
+	git pack-objects .git/objects/pack/mypackname1 >packhash1 <objects &&
+
+	git rev-parse HEAD~ HEAD~^{tree} HEAD:five.t >objects &&
+	git pack-objects .git/objects/pack/mypackname2 >packhash2 <objects &&
+
+	head_commit_pack=$(test-tool find-pack HEAD) &&
+
+	# HEAD^{tree} is in 2 packfiles
+	test-tool find-pack HEAD^{tree} >head_tree_packs &&
+	grep "$head_commit_pack" head_tree_packs &&
+	grep mypackname1 head_tree_packs &&
+	! grep mypackname2 head_tree_packs &&
+	test-tool find-pack --check-count 2 HEAD^{tree} &&
+	! test-tool find-pack --check-count 1 HEAD^{tree} &&
+
+	# HEAD:five.t is also in 2 packfiles
+	test-tool find-pack HEAD:five.t >five_packs &&
+	grep "$head_commit_pack" five_packs &&
+	! grep mypackname1 five_packs &&
+	grep mypackname2 five_packs &&
+	test-tool find-pack -c 2 HEAD:five.t &&
+	! test-tool find-pack --check-count=0 HEAD:five.t
+'
+
+test_expect_success 'add more commits (as loose objects)' '
+	test_commit six &&
+	test_commit seven &&
+
+	test -z "$(test-tool find-pack HEAD)" &&
+	test -z "$(test-tool find-pack HEAD:six.t)" &&
+	test-tool find-pack --check-count 0 HEAD &&
+	test-tool find-pack -c 0 HEAD:six.t &&
+	! test-tool find-pack -c 1 HEAD:seven.t
+'
+
+test_done
diff --git a/t/t5317-pack-objects-filter-objects.sh b/t/t5317-pack-objects-filter-objects.sh
index b26d476c64..2ff3eef9a3 100755
--- a/t/t5317-pack-objects-filter-objects.sh
+++ b/t/t5317-pack-objects-filter-objects.sh
@@ -53,6 +53,14 @@ test_expect_success 'verify blob:none packfile has no blobs' '
 	! grep blob verify_result
 '
 
+test_expect_success 'verify blob:none packfile without --stdout' '
+	git -C r1 pack-objects --revs --filter=blob:none mypackname >packhash <<-EOF &&
+	HEAD
+	EOF
+	git -C r1 verify-pack -v "mypackname-$(cat packhash).pack" >verify_result &&
+	! grep blob verify_result
+'
+
 test_expect_success 'verify normal and blob:none packfiles have same commits/trees' '
 	git -C r1 verify-pack -v ../all.pack >verify_result &&
 	grep -E "commit|tree" verify_result |
diff --git a/t/t6500-gc.sh b/t/t6500-gc.sh
index 69509d0c11..e412cf8daf 100755
--- a/t/t6500-gc.sh
+++ b/t/t6500-gc.sh
@@ -202,6 +202,30 @@ test_expect_success 'one of gc.reflogExpire{Unreachable,}=never does not skip "e
 	grep -E "^trace: (built-in|exec|run_command): git reflog expire --" trace.out
 '
 
+test_expect_success 'gc.repackFilter launches repack with a filter' '
+	git clone --no-local --bare . bare.git &&
+
+	git -C bare.git -c gc.cruftPacks=false gc &&
+	test_stdout_line_count = 1 ls bare.git/objects/pack/*.pack &&
+
+	GIT_TRACE=$(pwd)/trace.out git -C bare.git -c gc.repackFilter=blob:none \
+		-c repack.writeBitmaps=false -c gc.cruftPacks=false gc &&
+	test_stdout_line_count = 2 ls bare.git/objects/pack/*.pack &&
+	grep -E "^trace: (built-in|exec|run_command): git repack .* --filter=blob:none ?.*" trace.out
+'
+
+test_expect_success 'gc.repackFilterTo store filtered out objects' '
+	test_when_finished "rm -rf bare.git filtered.git" &&
+
+	git init --bare filtered.git &&
+	git -C bare.git -c gc.repackFilter=blob:none \
+		-c gc.repackFilterTo=../filtered.git/objects/pack/pack \
+		-c repack.writeBitmaps=false -c gc.cruftPacks=false gc &&
+
+	test_stdout_line_count = 1 ls bare.git/objects/pack/*.pack &&
+	test_stdout_line_count = 1 ls filtered.git/objects/pack/*.pack
+'
+
 prepare_cruft_history () {
 	test_commit base &&
 
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 27b66807cd..48e92aa6f7 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -327,6 +327,203 @@ test_expect_success 'auto-bitmaps do not complain if unavailable' '
 	test_must_be_empty actual
 '
 
+test_expect_success 'repacking with a filter works' '
+	git -C bare.git repack -a -d &&
+	test_stdout_line_count = 1 ls bare.git/objects/pack/*.pack &&
+	git -C bare.git -c repack.writebitmaps=false repack -a -d --filter=blob:none &&
+	test_stdout_line_count = 2 ls bare.git/objects/pack/*.pack &&
+	commit_pack=$(test-tool -C bare.git find-pack -c 1 HEAD) &&
+	blob_pack=$(test-tool -C bare.git find-pack -c 1 HEAD:file1) &&
+	test "$commit_pack" != "$blob_pack" &&
+	tree_pack=$(test-tool -C bare.git find-pack -c 1 HEAD^{tree}) &&
+	test "$tree_pack" = "$commit_pack" &&
+	blob_pack2=$(test-tool -C bare.git find-pack -c 1 HEAD:file2) &&
+	test "$blob_pack2" = "$blob_pack"
+'
+
+test_expect_success '--filter fails with --write-bitmap-index' '
+	test_must_fail \
+		env GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=0 \
+		git -C bare.git repack -a -d --write-bitmap-index --filter=blob:none
+'
+
+test_expect_success 'repacking with two filters works' '
+	git init two-filters &&
+	(
+		cd two-filters &&
+		mkdir subdir &&
+		test_commit foo &&
+		test_commit subdir_bar subdir/bar &&
+		test_commit subdir_baz subdir/baz
+	) &&
+	git clone --no-local --bare two-filters two-filters.git &&
+	(
+		cd two-filters.git &&
+		test_stdout_line_count = 1 ls objects/pack/*.pack &&
+		git -c repack.writebitmaps=false repack -a -d \
+			--filter=blob:none --filter=tree:1 &&
+		test_stdout_line_count = 2 ls objects/pack/*.pack &&
+		commit_pack=$(test-tool find-pack -c 1 HEAD) &&
+		blob_pack=$(test-tool find-pack -c 1 HEAD:foo.t) &&
+		root_tree_pack=$(test-tool find-pack -c 1 HEAD^{tree}) &&
+		subdir_tree_hash=$(git ls-tree --object-only HEAD -- subdir) &&
+		subdir_tree_pack=$(test-tool find-pack -c 1 "$subdir_tree_hash") &&
+
+		# Root tree and subdir tree are not in the same packfiles
+		test "$commit_pack" != "$blob_pack" &&
+		test "$commit_pack" = "$root_tree_pack" &&
+		test "$blob_pack" = "$subdir_tree_pack"
+	)
+'
+
+prepare_for_keep_packs () {
+	git init keep-packs &&
+	(
+		cd keep-packs &&
+		test_commit foo &&
+		test_commit bar
+	) &&
+	git clone --no-local --bare keep-packs keep-packs.git &&
+	(
+		cd keep-packs.git &&
+
+		# Create two packs
+		# The first pack will contain all of the objects except one blob
+		git rev-list --objects --all >objs &&
+		grep -v "bar.t" objs | git pack-objects pack &&
+		# The second pack will contain the excluded object and be kept
+		packid=$(grep "bar.t" objs | git pack-objects pack) &&
+		>pack-$packid.keep &&
+
+		# Replace the existing pack with the 2 new ones
+		rm -f objects/pack/pack* &&
+		mv pack-* objects/pack/
+	)
+}
+
+test_expect_success '--filter works with .keep packs' '
+	prepare_for_keep_packs &&
+	(
+		cd keep-packs.git &&
+
+		foo_pack=$(test-tool find-pack -c 1 HEAD:foo.t) &&
+		bar_pack=$(test-tool find-pack -c 1 HEAD:bar.t) &&
+		head_pack=$(test-tool find-pack -c 1 HEAD) &&
+
+		test "$foo_pack" != "$bar_pack" &&
+		test "$foo_pack" = "$head_pack" &&
+
+		git -c repack.writebitmaps=false repack -a -d --filter=blob:none &&
+
+		foo_pack_1=$(test-tool find-pack -c 1 HEAD:foo.t) &&
+		bar_pack_1=$(test-tool find-pack -c 1 HEAD:bar.t) &&
+		head_pack_1=$(test-tool find-pack -c 1 HEAD) &&
+
+		# Object bar is still only in the old .keep pack
+		test "$foo_pack_1" != "$foo_pack" &&
+		test "$bar_pack_1" = "$bar_pack" &&
+		test "$head_pack_1" != "$head_pack" &&
+
+		test "$foo_pack_1" != "$bar_pack_1" &&
+		test "$foo_pack_1" != "$head_pack_1" &&
+		test "$bar_pack_1" != "$head_pack_1"
+	)
+'
+
+test_expect_success '--filter works with --pack-kept-objects and .keep packs' '
+	rm -rf keep-packs keep-packs.git &&
+	prepare_for_keep_packs &&
+	(
+		cd keep-packs.git &&
+
+		foo_pack=$(test-tool find-pack -c 1 HEAD:foo.t) &&
+		bar_pack=$(test-tool find-pack -c 1 HEAD:bar.t) &&
+		head_pack=$(test-tool find-pack -c 1 HEAD) &&
+
+		test "$foo_pack" != "$bar_pack" &&
+		test "$foo_pack" = "$head_pack" &&
+
+		git -c repack.writebitmaps=false repack -a -d --filter=blob:none \
+			--pack-kept-objects &&
+
+		foo_pack_1=$(test-tool find-pack -c 1 HEAD:foo.t) &&
+		test-tool find-pack -c 2 HEAD:bar.t >bar_pack_1 &&
+		head_pack_1=$(test-tool find-pack -c 1 HEAD) &&
+
+		test "$foo_pack_1" != "$foo_pack" &&
+		test "$foo_pack_1" != "$bar_pack" &&
+		test "$head_pack_1" != "$head_pack" &&
+
+		# Object bar is in both the old .keep pack and the new
+		# pack that contained the filtered out objects
+		grep "$bar_pack" bar_pack_1 &&
+		grep "$foo_pack_1" bar_pack_1 &&
+		test "$foo_pack_1" != "$head_pack_1"
+	)
+'
+
+test_expect_success '--filter-to stores filtered out objects' '
+	git -C bare.git repack -a -d &&
+	test_stdout_line_count = 1 ls bare.git/objects/pack/*.pack &&
+
+	git init --bare filtered.git &&
+	git -C bare.git -c repack.writebitmaps=false repack -a -d \
+		--filter=blob:none \
+		--filter-to=../filtered.git/objects/pack/pack &&
+	test_stdout_line_count = 1 ls bare.git/objects/pack/pack-*.pack &&
+	test_stdout_line_count = 1 ls filtered.git/objects/pack/pack-*.pack &&
+
+	commit_pack=$(test-tool -C bare.git find-pack -c 1 HEAD) &&
+	blob_pack=$(test-tool -C bare.git find-pack -c 0 HEAD:file1) &&
+	blob_hash=$(git -C bare.git rev-parse HEAD:file1) &&
+	test -n "$blob_hash" &&
+	blob_pack=$(test-tool -C filtered.git find-pack -c 1 $blob_hash) &&
+
+	echo $(pwd)/filtered.git/objects >bare.git/objects/info/alternates &&
+	blob_pack=$(test-tool -C bare.git find-pack -c 1 HEAD:file1) &&
+	blob_content=$(git -C bare.git show $blob_hash) &&
+	test "$blob_content" = "content1"
+'
+
+test_expect_success '--filter works with --max-pack-size' '
+	rm -rf filtered.git &&
+	git init --bare filtered.git &&
+	git init max-pack-size &&
+	(
+		cd max-pack-size &&
+		test_commit base &&
+		# two blobs which exceed the maximum pack size
+		test-tool genrandom foo 1048576 >foo &&
+		git hash-object -w foo &&
+		test-tool genrandom bar 1048576 >bar &&
+		git hash-object -w bar &&
+		git add foo bar &&
+		git commit -m "adding foo and bar"
+	) &&
+	git clone --no-local --bare max-pack-size max-pack-size.git &&
+	(
+		cd max-pack-size.git &&
+		git -c repack.writebitmaps=false repack -a -d --filter=blob:none \
+			--max-pack-size=1M \
+			--filter-to=../filtered.git/objects/pack/pack &&
+		echo $(cd .. && pwd)/filtered.git/objects >objects/info/alternates &&
+
+		# Check that the 3 blobs are in different packfiles in filtered.git
+		test_stdout_line_count = 3 ls ../filtered.git/objects/pack/pack-*.pack &&
+		test_stdout_line_count = 1 ls objects/pack/pack-*.pack &&
+		foo_pack=$(test-tool find-pack -c 1 HEAD:foo) &&
+		bar_pack=$(test-tool find-pack -c 1 HEAD:bar) &&
+		base_pack=$(test-tool find-pack -c 1 HEAD:base.t) &&
+		test "$foo_pack" != "$bar_pack" &&
+		test "$foo_pack" != "$base_pack" &&
+		test "$bar_pack" != "$base_pack" &&
+		for pack in "$foo_pack" "$bar_pack" "$base_pack"
+		do
+			case "$foo_pack" in */filtered.git/objects/pack/*) true ;; *) return 1 ;; esac
+		done
+	)
+'
+
 objdir=.git/objects
 midx=$objdir/pack/multi-pack-index