diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 973b6c7d482..5eac36500d4 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -282,8 +282,8 @@ option is given with no value, it's enabled.
 ** 'unfold[=<BOOL>]': make it behave as if interpret-trailer's `--unfold`
    option was given. E.g.,
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
-** 'valueonly[=<BOOL>]': skip over the key part of the trailer line and only
-   show the value part.
+** 'keyonly[=<BOOL>]': only show the key part of the trailer.
+** 'valueonly[=<BOOL>]': only show the value part of the trailer.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will
diff --git a/pretty.c b/pretty.c
index 7a7708a0ea7..1237ee0e45d 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1451,6 +1451,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 					opts.separator = &sepbuf;
 				} else if (!match_placeholder_bool_arg(arg, "only", &arg, &opts.only_trailers) &&
 					   !match_placeholder_bool_arg(arg, "unfold", &arg, &opts.unfold) &&
+					   !match_placeholder_bool_arg(arg, "keyonly", &arg, &opts.key_only) &&
 					   !match_placeholder_bool_arg(arg, "valueonly", &arg, &opts.value_only))
 					break;
 			}
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index cb09a13249e..4c9f6eb7946 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -715,6 +715,22 @@ test_expect_success '%(trailers:key) without value is error' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:keyonly) shows only keys' '
+	git log --no-walk --pretty="format:%(trailers:keyonly)" >actual &&
+	test_write_lines \
+		"Signed-off-by" \
+		"Acked-by" \
+		"[ v2 updated patch description ]" \
+		"Signed-off-by" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(trailers:key=foo,keyonly) shows only key' '
+	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly)" >actual &&
+	echo "Acked-by" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 	git log --no-walk --pretty="format:%(trailers:key=Acked-by,valueonly)" >actual &&
 	echo "A U Thor <author@example.com>" >expect &&
@@ -732,6 +748,12 @@ test_expect_success '%(trailers:valueonly) shows only values' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:key=foo,keyonly,valueonly) shows nothing' '
+	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly,valueonly)" >actual &&
+	echo >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00)X" >actual &&
 	(
@@ -754,7 +776,7 @@ test_expect_success 'pretty format %(trailers:separator=X,unfold) changes separa
 	test_cmp expect actual
 '
 
-test_expect_success 'pretty format %(trailers) combining separator/key/valueonly' '
+test_expect_success 'pretty format %(trailers) combining separator/key/keyonly/valueonly' '
 	git commit --allow-empty -F - <<-\EOF &&
 	Important fix
 
@@ -781,6 +803,13 @@ test_expect_success 'pretty format %(trailers) combining separator/key/valueonly
 		"Does not close any tickets" \
 		"Another fix #567, #890" \
 		"Important fix #1234" >expect &&
+	test_cmp expect actual &&
+
+	git log --pretty="%s% (trailers:separator=%x2c%x20,key=Closes,keyonly)" HEAD~3.. >actual &&
+	test_write_lines \
+		"Does not close any tickets" \
+		"Another fix Closes, Closes" \
+		"Important fix Closes" >expect &&
 	test_cmp expect actual
 '
 
diff --git a/trailer.c b/trailer.c
index d2d01015b1d..889b419a4f6 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1132,7 +1132,7 @@ static void format_trailer_info(struct strbuf *out,
 
 	/* If we want the whole block untouched, we can take the fast path. */
 	if (!opts->only_trailers && !opts->unfold && !opts->filter &&
-	    !opts->separator && !opts->value_only) {
+	    !opts->separator && !opts->key_only && !opts->value_only) {
 		strbuf_add(out, info->trailer_start,
 			   info->trailer_end - info->trailer_start);
 		return;
@@ -1154,8 +1154,11 @@ static void format_trailer_info(struct strbuf *out,
 				if (opts->separator && out->len != origlen)
 					strbuf_addbuf(out, opts->separator);
 				if (!opts->value_only)
-					strbuf_addf(out, "%s: ", tok.buf);
-				strbuf_addbuf(out, &val);
+					strbuf_addbuf(out, &tok);
+				if (!opts->key_only && !opts->value_only)
+					strbuf_addstr(out, ": ");
+				if (!opts->key_only)
+					strbuf_addbuf(out, &val);
 				if (!opts->separator)
 					strbuf_addch(out, '\n');
 			}
diff --git a/trailer.h b/trailer.h
index cd93e7ddea7..d2f28776be6 100644
--- a/trailer.h
+++ b/trailer.h
@@ -71,6 +71,7 @@ struct process_trailer_options {
 	int only_input;
 	int unfold;
 	int no_divider;
+	int key_only;
 	int value_only;
 	const struct strbuf *separator;
 	int (*filter)(const struct strbuf *, void *);
