diff --git a/t/helper/test-path-utils.c b/t/helper/test-path-utils.c
index 30211d6d64..6efde6f5ba 100644
--- a/t/helper/test-path-utils.c
+++ b/t/helper/test-path-utils.c
@@ -303,6 +303,27 @@ int cmd__path_utils(int argc, const char **argv)
 		return !!res;
 	}
 
+	if (argc == 4 && !strcmp(argv[1], "skip-n-bytes")) {
+		int fd = open(argv[2], O_RDONLY), offset = atoi(argv[3]);
+		char buffer[65536];
+
+		if (fd < 0)
+			die_errno("could not open '%s'", argv[2]);
+		if (lseek(fd, offset, SEEK_SET) < 0)
+			die_errno("could not skip %d bytes", offset);
+		for (;;) {
+			ssize_t count = read(fd, buffer, sizeof(buffer));
+			if (count < 0)
+				die_errno("could not read '%s'", argv[2]);
+			if (!count)
+				break;
+			if (write(1, buffer, count) < 0)
+				die_errno("could not write to stdout");
+		}
+		close(fd);
+		return 0;
+	}
+
 	fprintf(stderr, "%s: unknown function name: %s\n", argv[0],
 		argv[1] ? argv[1] : "(there was none)");
 	return 1;
diff --git a/t/test-lib.sh b/t/test-lib.sh
index a3b2166cb5..f31a1c8f79 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -639,8 +639,19 @@ test_failure_ () {
 		junit_insert="<failure message=\"not ok $test_count -"
 		junit_insert="$junit_insert $(xml_attr_encode "$1")\">"
 		junit_insert="$junit_insert $(xml_attr_encode \
-			"$(printf '%s\n' "$@" | sed 1d)")"
+			"$(if test -n "$GIT_TEST_TEE_OUTPUT_FILE"
+			   then
+				test-tool path-utils skip-n-bytes \
+					"$GIT_TEST_TEE_OUTPUT_FILE" $GIT_TEST_TEE_OFFSET
+			   else
+				printf '%s\n' "$@" | sed 1d
+			   fi)")"
 		junit_insert="$junit_insert</failure>"
+		if test -n "$GIT_TEST_TEE_OUTPUT_FILE"
+		then
+			junit_insert="$junit_insert<system-err>$(xml_attr_encode \
+				"$(cat "$GIT_TEST_TEE_OUTPUT_FILE")")</system-err>"
+		fi
 		write_junit_xml_testcase "$1" "      $junit_insert"
 	fi
 	test_failure=$(($test_failure + 1))
@@ -931,6 +942,11 @@ test_finish_ () {
 	echo >&3 ""
 	maybe_teardown_valgrind
 	maybe_teardown_verbose
+	if test -n "$GIT_TEST_TEE_OFFSET"
+	then
+		GIT_TEST_TEE_OFFSET=$(test-tool path-utils file-size \
+			"$GIT_TEST_TEE_OUTPUT_FILE")
+	fi
 }
 
 test_skip () {
@@ -1280,6 +1296,10 @@ then
 		date +%Y-%m-%dT%H:%M:%S)\""
 	write_junit_xml --truncate "<testsuites>" "  <testsuite $junit_attrs>"
 	junit_suite_start=$(test-tool date getnanos)
+	if test -n "$GIT_TEST_TEE_OUTPUT_FILE"
+	then
+		GIT_TEST_TEE_OFFSET=0
+	fi
 fi
 
 # Provide an implementation of the 'yes' utility