diff --git a/Documentation/git-repack.adoc b/Documentation/git-repack.adoc
index 72c42015e2..04ef2ad49a 100644
--- a/Documentation/git-repack.adoc
+++ b/Documentation/git-repack.adoc
@@ -45,8 +45,8 @@ other objects in that pack they already have locally.
 +
 Promisor packfiles are repacked separately: if there are packfiles that
 have an associated ".promisor" file, these packfiles will be repacked
-into another separate pack, and an empty ".promisor" file corresponding
-to the new separate pack will be written.
+into another separate pack, and a ".promisor" file corresponding to the
+new separate pack will be written (with arbitrary contents).
 
 -A::
 	Same as `-a`, unless `-d` is used.  Then any unreachable
diff --git a/pack-write.c b/pack-write.c
index 83eaf88541..b8ab9510ff 100644
--- a/pack-write.c
+++ b/pack-write.c
@@ -603,6 +603,15 @@ void write_promisor_file(const char *promisor_name, struct ref **sought, int nr_
 	int i, err;
 	FILE *output = xfopen(promisor_name, "w");
 
+	/*
+	 * Write in the .promisor file the ref names and associated hashes,
+	 * obtained by fetch-pack, at the point of generation of the
+	 * corresponding packfile. These pieces of info are only used to make
+	 * it easier to debug issues with partial clones, as we can identify
+	 * what refs (and their associated hashes) were fetched at the time
+	 * the packfile was downloaded, and if necessary, compare those hashes
+	 * against what the promisor remote reports now.
+	 */
 	for (i = 0; i < nr_sought; i++)
 		fprintf(output, "%s %s\n", oid_to_hex(&sought[i]->old_oid),
 			sought[i]->name);
diff --git a/repack-promisor.c b/repack-promisor.c
index 90318ce150..472aef0081 100644
--- a/repack-promisor.c
+++ b/repack-promisor.c
@@ -1,11 +1,18 @@
 #include "git-compat-util.h"
 #include "repack.h"
+#include "hash.h"
 #include "hex.h"
+#include "odb.h"
 #include "pack.h"
 #include "packfile.h"
 #include "path.h"
+#include "refs.h"
 #include "repository.h"
 #include "run-command.h"
+#include "strbuf.h"
+#include "string-list.h"
+#include "strmap.h"
+#include "strvec.h"
 
 struct write_oid_context {
 	struct child_process *cmd;
@@ -34,10 +41,159 @@ static int write_oid(const struct object_id *oid,
 	return 0;
 }
 
+/*
+ * Go through all .promisor files contained in repo (excluding those whose name
+ * appears in not_repacked_basenames, which acts as a ignorelist), and copies
+ * their content inside the destination file "<packtmp>-<dest_hex>.promisor".
+ * Each line of a never repacked .promisor file is: "<oid> <ref>" (as described
+ * in the write_promisor_file() function).
+ * After a repack, the copied lines will be: "<oid> <ref> <time>", where <time>
+ * is the time (in Unix time) at which the .promisor file was last modified.
+ * Only the lines whose <oid> is present inside "<packtmp>-<dest_hex>.idx" will
+ * be copied.
+ * The contents of all .promisor files are assumed to be correctly formed.
+ */
+static void write_promisor_file_after_repack(struct repository *repo,
+								const char *dest_hex,
+								const char *packtmp,
+								struct strset *not_repacked_basenames)
+{
+	char *dest_promisor_name;
+	char *dest_idx_name;
+	FILE *dest;
+	struct object_id dest_oid;
+	struct packed_git *dest_pack, *p;
+	struct strbuf source_promisor_name = STRBUF_INIT;
+	struct strset seen_lines = STRSET_INIT;
+	struct strbuf line = STRBUF_INIT;
+	int err;
+
+	/* First of all, let's create and open the .promisor dest file */
+	dest_promisor_name = mkpathdup("%s-%s.promisor", packtmp, dest_hex);
+	dest = xfopen(dest_promisor_name, "w");
+
+	/*
+	 * Now let's retrieve the destination pack.
+	 * We use parse_pack_index() because dest_hex/packtmp point to the packfile
+	 * that "pack-objects" just created, which is about to become part of this
+	 * repository, but has not yet been finalized.
+	 * If we are here, we know that "pack-objects" did not fail, so
+	 * parse_pack_index() being loose in validation does not pose a problem.
+	 * If an error happens, we simply leave the ".promisor" file empty.
+	 */
+	if (get_oid_hex_algop(dest_hex, &dest_oid, repo->hash_algo)) {
+		warning(_("Promisor file left empty: '%s' not a hash"), dest_hex);
+		if (fclose(dest))
+			die(_("Could not close '%s' promisor file"), dest_promisor_name);
+		free(dest_promisor_name);
+		return;
+	}
+	dest_idx_name = mkpathdup("%s-%s.idx", packtmp, dest_hex);
+	dest_pack = parse_pack_index(repo, dest_oid.hash, dest_idx_name);
+	if (!dest_pack) {
+		warning(_("Promisor file left empty: couldn't open packfile '%s'"), dest_idx_name);
+		if (fclose(dest))
+			die(_("Could not close '%s' promisor file"), dest_promisor_name);
+		free(dest_promisor_name);
+		free(dest_idx_name);
+		return;
+	}
+
+	repo_for_each_pack(repo, p) {
+		FILE *source;
+		struct stat source_stat;
+
+		if (!p->pack_promisor)
+			continue;
+
+		if (not_repacked_basenames &&
+			strset_contains(not_repacked_basenames, pack_basename(p)))
+			continue;
+
+		strbuf_reset(&source_promisor_name);
+		strbuf_addstr(&source_promisor_name, p->pack_name);
+		strbuf_strip_suffix(&source_promisor_name, ".pack");
+		strbuf_addstr(&source_promisor_name, ".promisor");
+
+		if (stat(source_promisor_name.buf, &source_stat))
+			die(_("File not found: %s"), source_promisor_name.buf);
+
+		source = xfopen(source_promisor_name.buf, "r");
+
+		while (strbuf_getline(&line, source) != EOF) {
+			struct string_list line_sections = STRING_LIST_INIT_DUP;
+			struct object_id oid;
+
+			/* Split line into <oid>, <ref> and <time> (if <time> exists).
+			 * Check that it was actually split into 2 or 3 parts. If it was
+			 *  not, then it is malformed, so skip it.
+			 */
+			string_list_split(&line_sections, line.buf, " ", 3);
+			if (line_sections.nr != 2 && line_sections.nr != 3) {
+				string_list_clear(&line_sections, 0);
+				continue;
+			}
+
+			/* Skip the lines where <oid> is not a sane hexadecimal string */
+			if (get_oid_hex_algop(line_sections.items[0].string,
+						&oid, repo->hash_algo)) {
+				string_list_clear(&line_sections, 0);
+				continue;
+			}
+			/* Ignore the lines where <oid> doesn't appear in the dest_pack */
+			if (!find_pack_entry_one(&oid, dest_pack)) {
+				string_list_clear(&line_sections, 0);
+				continue;
+			}
+
+			/*
+			 * Skip the lines where <ref> does not have the
+			 * correct format for a refname.
+			 */
+			printf("%s\n", line_sections.items[1].string);
+			if (check_refname_format(line_sections.items[1].string,
+							REFNAME_ALLOW_ONELEVEL)) {
+				string_list_clear(&line_sections, 0);
+				continue;
+			}
+
+			/* If <time> doesn't exist, retrieve it and add it to line */
+			if (line_sections.nr != 3)
+				strbuf_addf(&line, " %" PRItime,
+							(timestamp_t)source_stat.st_mtime);
+
+			/* If the finalized line is new, append it to dest */
+			if (strset_add(&seen_lines, line.buf))
+				fprintf(dest, "%s\n", line.buf);
+
+			string_list_clear(&line_sections, 0);
+		}
+
+		err = ferror(source);
+		err |= fclose(source);
+		if (err)
+			die(_("Could not read '%s' promisor file"), source_promisor_name.buf);
+	}
+
+	err = ferror(dest);
+	err |= fclose(dest);
+	if (err)
+		die(_("Could not write '%s' promisor file"), dest_promisor_name);
+
+	close_pack_index(dest_pack);
+	free(dest_pack);
+	free(dest_promisor_name);
+	free(dest_idx_name);
+	strbuf_release(&source_promisor_name);
+	strbuf_release(&line);
+	strset_clear(&seen_lines);
+}
+
 static void finish_repacking_promisor_objects(struct repository *repo,
 					      struct child_process *cmd,
 					      struct string_list *names,
-					      const char *packtmp)
+					      const char *packtmp,
+					      struct strset *not_repacked_basenames)
 {
 	struct strbuf line = STRBUF_INIT;
 	FILE *out;
@@ -47,7 +203,6 @@ static void finish_repacking_promisor_objects(struct repository *repo,
 	out = xfdopen(cmd->out, "r");
 	while (strbuf_getline_lf(&line, out) != EOF) {
 		struct string_list_item *item;
-		char *promisor_name;
 
 		if (line.len != repo->hash_algo->hexsz)
 			die(_("repack: Expecting full hex object ID lines only from pack-objects."));
@@ -55,22 +210,16 @@ static void finish_repacking_promisor_objects(struct repository *repo,
 
 		/*
 		 * pack-objects creates the .pack and .idx files, but not the
-		 * .promisor file. Create the .promisor file, which is empty.
-		 *
-		 * NEEDSWORK: fetch-pack sometimes generates non-empty
-		 * .promisor files containing the ref names and associated
-		 * hashes at the point of generation of the corresponding
-		 * packfile, but this would not preserve their contents. Maybe
-		 * concatenate the contents of all .promisor files instead of
-		 * just creating a new empty file.
+		 * ".promisor" file. To create the "".promisor" file, we don't use the
+		 * helper function write_promisor_file(), but instead we use the
+		 * specific function write_promisor_file_after_repack(), which creates
+		 * the file and appropriately fills it with the content of the
+		 * ".promisor" files used for the repack.
 		 */
-		promisor_name = mkpathdup("%s-%s.promisor", packtmp,
-					  line.buf);
-		write_promisor_file(promisor_name, NULL, 0);
+		write_promisor_file_after_repack(repo, line.buf, packtmp,
+						not_repacked_basenames);
 
 		item->util = generated_pack_populate(item->string, packtmp);
-
-		free(promisor_name);
 	}
 
 	fclose(out);
@@ -107,7 +256,7 @@ void repack_promisor_objects(struct repository *repo,
 		return;
 	}
 
-	finish_repacking_promisor_objects(repo, &cmd, names, packtmp);
+	finish_repacking_promisor_objects(repo, &cmd, names, packtmp, NULL);
 }
 
 void pack_geometry_repack_promisors(struct repository *repo,
@@ -118,6 +267,7 @@ void pack_geometry_repack_promisors(struct repository *repo,
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	FILE *in;
+	struct strset not_repacked_basenames = STRSET_INIT;
 
 	if (!geometry->promisor_split)
 		return;
@@ -131,9 +281,15 @@ void pack_geometry_repack_promisors(struct repository *repo,
 	in = xfdopen(cmd.in, "w");
 	for (size_t i = 0; i < geometry->promisor_split; i++)
 		fprintf(in, "%s\n", pack_basename(geometry->promisor_pack[i]));
-	for (size_t i = geometry->promisor_split; i < geometry->promisor_pack_nr; i++)
-		fprintf(in, "^%s\n", pack_basename(geometry->promisor_pack[i]));
+	for (size_t i = geometry->promisor_split; i < geometry->promisor_pack_nr; i++) {
+		const char *name = pack_basename(geometry->promisor_pack[i]);
+		fprintf(in, "^%s\n", name);
+		strset_add(&not_repacked_basenames, name);
+	}
 	fclose(in);
 
-	finish_repacking_promisor_objects(repo, &cmd, names, packtmp);
+	finish_repacking_promisor_objects(repo, &cmd, names, packtmp,
+			strset_get_size(&not_repacked_basenames) ? &not_repacked_basenames : NULL);
+
+	strset_clear(&not_repacked_basenames);
 }
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 63ef63fc50..1decd7520a 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -904,4 +904,65 @@ test_expect_success 'pending objects are repacked appropriately' '
 	)
 '
 
+test_expect_success 'check one .promisor file content after repack' '
+	test_when_finished rm -rf prom_test prom_before_repack &&
+	git init prom_test &&
+	path=prom_test/.git/objects/pack &&
+
+	(
+		# Create 1 pack
+		test_commit_bulk -C prom_test 1 &&
+
+		# Simulate .promisor file by creating it manually
+		prom=$(find $path -name "*.pack" | sed "s/.pack$/.promisor/") &&
+		oid=$(git -C prom_test rev-parse HEAD) &&
+		echo "$oid ref" >"$prom" &&
+
+		# Repack, and check if correct
+		git -C prom_test repack -a -d -f &&
+		prom=$(find $path -name "*.promisor") &&
+		# $prom should contain "$oid ref <time>"
+		test_grep "$oid ref " "$prom" &&
+
+		# Save the current .promisor content, repack, and check if correct
+		cp "$prom" prom_before_repack &&
+		git -C prom_test repack -a -d -f &&
+		prom=$(find $path -name "*.promisor") &&
+		# $prom should be exactly the same as prom_before_repack
+		test_cmp prom_before_repack "$prom"
+	)
+'
+
+test_expect_success 'check multiple .promisor file content after repack' '
+	test_when_finished rm -rf prom_test prom_before_repack &&
+	git init prom_test &&
+	path=prom_test/.git/objects/pack &&
+
+	(
+		# Create 2 packs and simulate .promisor files by creating them manually
+		test_commit_bulk -C prom_test 1 &&
+		prom=$(find $path -name "*.pack" | sed "s/.pack$/.promisor/") &&
+		oid1=$(git -C prom_test rev-parse HEAD) &&
+		echo "$oid1 ref1" >"$prom" &&
+		test_commit_bulk -C prom_test 1 &&
+		prom=$(find $path -name "*.pack" | sed "s/.pack$/.promisor/; \|$prom|d") &&
+		oid2=$(git -C prom_test rev-parse HEAD) &&
+		echo "$oid2 ref2" >"$prom" &&
+
+		# Repack, and check if correct
+		git -C prom_test repack -a -d -f &&
+		prom=$(find $path -name "*.promisor") &&
+		# $prom should contain "$oid1 ref1 <time>" & "$oid2 ref2 <time>"
+		test_grep "$oid1 ref1 " "$prom" &&
+		test_grep "$oid2 ref2 " "$prom" &&
+
+		# Save the current .promisor content, repack, and check if correct
+		cp "$prom" prom_before_repack &&
+		git -C prom_test repack -a -d -f &&
+		prom=$(find $path -name "*.promisor") &&
+		# $prom should be exactly the same as prom_before_repack
+		test_cmp prom_before_repack "$prom"
+	)
+'
+
 test_done
diff --git a/t/t7703-repack-geometric.sh b/t/t7703-repack-geometric.sh
index 04d5d8fc33..316247a3b9 100755
--- a/t/t7703-repack-geometric.sh
+++ b/t/t7703-repack-geometric.sh
@@ -541,4 +541,37 @@ test_expect_success 'geometric repack works with promisor packs' '
 	)
 '
 
+test_expect_success 'check .promisor file content after geometric repack' '
+	test_when_finished rm -rf prom_test &&
+	git init prom_test &&
+	path=prom_test/.git/objects/pack &&
+
+	(
+		# Create 2 packs with 3 objs each, and manually create .promisor files
+		test_commit_bulk -C prom_test --start=1 1 &&  # 3 objects
+		prom1=$(find $path -name "*.pack" | sed "s/.pack$/.promisor/") &&
+		oid1=$(git -C prom_test rev-parse HEAD) &&
+		echo "$oid1 ref1" >"$prom1" &&
+		test_commit_bulk -C prom_test --start=2 1 &&  # 3 objects
+		prom2=$(find $path -name "*.pack" | sed "s/.pack$/.promisor/; \|$prom1|d") &&
+		oid2=$(git -C prom_test rev-parse HEAD) &&
+		echo "$oid2 ref2" >"$prom2" &&
+
+		# Create 1 pack with 12 objs, and manually create .promisor file
+		test_commit_bulk -C prom_test --start=3 4 &&  # 12 objects
+		prom3=$(find $path -name "*.pack" | sed "s/.pack$/.promisor/; \|$prom1|d; \|$prom2|d") &&
+		oid3=$(git -C prom_test rev-parse HEAD) &&
+		echo "$oid3 ref3" >"$prom3" &&
+
+		# Geometric repack, and check if correct
+		git -C prom_test repack --geometric 2 -d &&
+		prom=$(find $path -name "*.pack" | sed "s/.pack$/.promisor/; \|$prom3|d") &&
+		# $prom should have repacked only the first 2 small packs, so it should only
+		# contain the following: "$oid1 ref1 <time>" & "$oid2 ref2 <time>"
+		test_grep "$oid1 ref1 " "$prom" &&
+		test_grep "$oid2 ref2 " "$prom" &&
+		test_grep ! "$oid3 ref3" "$prom"
+	)
+'
+
 test_done