diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt
index a7c1b0f60e..7115564f7d 100644
--- a/Documentation/git-gc.txt
+++ b/Documentation/git-gc.txt
@@ -96,6 +96,11 @@ be performed as well.
 	`.keep` files are consolidated into a single pack. When this
 	option is used, `gc.bigPackThreshold` is ignored.
 
+--assume-pack-keep-transitive::
+	Pass the `--assume-pack-keep-transitive` option to `git-repack`;
+	see linkgit:git-repack[1].
+
+
 CONFIGURATION
 -------------
 
diff --git a/Documentation/git-repack.txt b/Documentation/git-repack.txt
index 836d81457a..014812c4bb 100644
--- a/Documentation/git-repack.txt
+++ b/Documentation/git-repack.txt
@@ -169,6 +169,27 @@ depth is 4095.
 	Pass the `--sparse` option to `git-pack-objects`; see
 	linkgit:git-pack-objects[1].
 
+--assume-pack-keep-transitive::
+	This flag accelerates the search for objects to pack by assuming
+	that commit objects found in kept packfiles make reference only
+	to that or other kept packfiles.  This is very useful if, for
+	example, this repository periodically repacks all reachable objects
+	and marks the resulting pack file as kept.
+
+	Because this option may prevent git from descending into kept packs,
+	no objects inside kept packs will be available for delta processing.
+	One should therefore restrict the use of this option to situations
+	where delta processing is disabled or when relatively large amounts
+	of data are considered and the relative gain of a wider set of
+	possible delta base objects is reduced.
+
+	The simplest way to ensure transitivity of kept packs is to run `git
+	repack` with `-a` (or `-A`) and `-d` and mark all resulting packs as
+	kept, never removing the kept marker.  In practice, one may wish to
+	wait to mark packs as kept until they are sufficiently large
+	(reducing the number of pack files necessary for a given set of
+	objects) but not so large as to be unwieldy.
+
 Configuration
 -------------
 
diff --git a/builtin/gc.c b/builtin/gc.c
index 020f725acc..1346afb3b1 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -49,6 +49,7 @@ static const char *prune_expire = "2.weeks.ago";
 static const char *prune_worktrees_expire = "3.months.ago";
 static unsigned long big_pack_threshold;
 static unsigned long max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE;
+static int assume_pack_keep_transitive;
 
 static struct argv_array pack_refs_cmd = ARGV_ARRAY_INIT;
 static struct argv_array reflog = ARGV_ARRAY_INIT;
@@ -526,6 +527,8 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_BOOL(0, "keep-largest-pack", &keep_base_pack,
 			 N_("repack all other packs except the largest pack")),
+		OPT_BOOL(0, "assume-pack-keep-transitive", &assume_pack_keep_transitive,
+			 N_("assume kept packs reference only kept packs")),
 		OPT_END()
 	};
 
@@ -564,6 +567,8 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	}
 	if (quiet)
 		argv_array_push(&repack, "-q");
+	if (assume_pack_keep_transitive)
+		argv_array_push(&repack, "--assume-pack-keep-transitive");
 
 	if (auto_gc) {
 		/*
diff --git a/builtin/repack.c b/builtin/repack.c
index 71e715b594..b2b407d42c 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -11,6 +11,8 @@
 #include "midx.h"
 #include "packfile.h"
 #include "object-store.h"
+#include "revision.h"
+#include "list-objects.h"
 
 static int delta_base_offset = 1;
 static int pack_kept_objects = -1;
@@ -261,6 +263,30 @@ static void repack_promisor_objects(const struct pack_objects_args *args,
 		die(_("could not finish pack-objects to repack promisor objects"));
 }
 
+static void apkt_show_commit(struct commit *commit, void *data)
+{
+	struct tree *tree;
+	struct pack_entry e;
+
+	if (!find_pack_entry(the_repository, &commit->object.oid, &e))
+		return;
+
+	if (!(e.p->pack_keep || e.p->pack_keep_in_core))
+		return;
+
+	tree = get_commit_tree(commit);
+	if (tree)
+		tree->object.flags |= UNINTERESTING;
+
+	write_oid(&commit->object.oid, e.p, 0, data);
+	write_oid(&tree->object.oid, NULL, 0, data);
+}
+
+static void apkt_show_object(struct object *obj, const char *name, void *data)
+{
+	return;
+}
+
 #define ALL_INTO_ONE 1
 #define LOOSEN_UNREACHABLE 2
 
@@ -292,6 +318,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	struct string_list keep_pack_list = STRING_LIST_INIT_NODUP;
 	int no_update_server_info = 0;
 	int midx_cleared = 0;
+	int assume_pack_keep_transitive = 0;
 	struct pack_objects_args po_args = {NULL};
 
 	struct option builtin_repack_options[] = {
@@ -333,6 +360,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 				N_("repack objects in packs marked with .keep")),
 		OPT_BOOL(0, "sparse", &sparse,
 			 N_("use the sparse reachability algorithm")),
+		OPT_BOOL(0, "assume-pack-keep-transitive", &assume_pack_keep_transitive,
+				N_("assume kept packs reference only kept packs")),
 		OPT_STRING_LIST(0, "keep-pack", &keep_pack_list, N_("name"),
 				N_("do not repack this pack")),
 		OPT_END()
@@ -351,6 +380,11 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	    (unpack_unreachable || (pack_everything & LOOSEN_UNREACHABLE)))
 		die(_("--keep-unreachable and -A are incompatible"));
 
+	if (assume_pack_keep_transitive) {
+		/* imply --honor-pack-keep */
+		pack_kept_objects = 0;
+	}
+
 	if (pack_kept_objects < 0)
 		pack_kept_objects = write_bitmaps;
 
@@ -374,7 +408,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	argv_array_push(&cmd.args, "--all");
 	argv_array_push(&cmd.args, "--reflog");
 	argv_array_push(&cmd.args, "--indexed-objects");
-	if (sparse)
+	if (sparse || assume_pack_keep_transitive)
 		argv_array_push(&cmd.args, "--sparse");
 	if (repository_format_partial_clone)
 		argv_array_push(&cmd.args, "--exclude-promisor-objects");
@@ -409,12 +443,30 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		argv_array_push(&cmd.args, "--incremental");
 	}
 
-	cmd.no_stdin = 1;
+	cmd.in = -1;
+	cmd.no_stdin = !assume_pack_keep_transitive;
 
 	ret = start_command(&cmd);
 	if (ret)
 		return ret;
 
+	if (assume_pack_keep_transitive) {
+		struct rev_info revs;
+		const char *revargv[] = { "skip", "--all", "--reflog", "--indexed-objects", NULL };
+
+		repo_init_revisions(the_repository, &revs, NULL);
+		setup_revisions(sizeof(revargv)/sizeof(revargv[0]) - 1 , revargv, &revs, NULL);
+		if (prepare_revision_walk(&revs, sparse))
+			die("revision walk setup failed");
+
+		xwrite(cmd.in, "--not\n", 6);
+		traverse_commit_list(&revs, apkt_show_commit, apkt_show_object,
+				     &cmd);
+		xwrite(cmd.in, "--not\n", 6);
+
+		close(cmd.in);
+	}
+
 	out = xfdopen(cmd.out, "r");
 	while (strbuf_getline_lf(&line, out) != EOF) {
 		if (line.len != the_hash_algo->hexsz)
