diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 17a268ccd1..502b4bcf9e 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -578,6 +578,78 @@ test_expect_success 'subtest: --run invalid range end' '
 	EOF_ERR
 '
 
+test_expect_success 'subtest: --invert-exit-code without --immediate' '
+	run_sub_test_lib_test_err full-pass \
+		--invert-exit-code &&
+	check_sub_test_lib_test_err full-pass \
+		<<-\EOF_OUT 3<<-EOF_ERR
+	ok 1 - passing test #1
+	ok 2 - passing test #2
+	ok 3 - passing test #3
+	# passed all 3 test(s)
+	1..3
+	# faking up non-zero exit with --invert-exit-code
+	EOF_OUT
+	EOF_ERR
+'
+
+test_expect_success 'subtest: --invert-exit-code with --immediate: all passed' '
+	run_sub_test_lib_test_err full-pass \
+		--invert-exit-code --immediate &&
+	check_sub_test_lib_test_err full-pass \
+		<<-\EOF_OUT 3<<-EOF_ERR
+	ok 1 - passing test #1
+	ok 2 - passing test #2
+	ok 3 - passing test #3
+	# passed all 3 test(s)
+	1..3
+	# faking up non-zero exit with --invert-exit-code
+	EOF_OUT
+	EOF_ERR
+'
+
+test_expect_success 'subtest: --invert-exit-code without --immediate: partial pass' '
+	run_sub_test_lib_test partial-pass \
+		--invert-exit-code &&
+	check_sub_test_lib_test partial-pass <<-\EOF
+	ok 1 - passing test #1
+	not ok 2 - # TODO induced breakage (--invert-exit-code): failing test #2
+	#	false
+	ok 3 - passing test #3
+	# failed 1 among 3 test(s)
+	1..3
+	# faked up failures as TODO & now exiting with 0 due to --invert-exit-code
+	EOF
+'
+
+test_expect_success 'subtest: --invert-exit-code with --immediate: partial pass' '
+	run_sub_test_lib_test partial-pass \
+		--invert-exit-code --immediate &&
+	check_sub_test_lib_test partial-pass \
+		<<-\EOF_OUT 3<<-EOF_ERR
+	ok 1 - passing test #1
+	not ok 2 - # TODO induced breakage (--invert-exit-code): failing test #2
+	#	false
+	1..2
+	# faked up failures as TODO & now exiting with 0 due to --invert-exit-code
+	EOF_OUT
+	EOF_ERR
+'
+
+test_expect_success 'subtest: --invert-exit-code --immediate: got a failure' '
+	run_sub_test_lib_test partial-pass \
+		--invert-exit-code --immediate &&
+	check_sub_test_lib_test_err partial-pass \
+		<<-\EOF_OUT 3<<-EOF_ERR
+	ok 1 - passing test #1
+	not ok 2 - # TODO induced breakage (--invert-exit-code): failing test #2
+	#	false
+	1..2
+	# faked up failures as TODO & now exiting with 0 due to --invert-exit-code
+	EOF_OUT
+	EOF_ERR
+'
+
 test_expect_success 'subtest: tests respect prerequisites' '
 	write_and_run_sub_test_lib_test prereqs <<-\EOF &&
 
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 118720493b..31213b5f95 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -238,6 +238,9 @@ parse_option () {
 			;;
 		esac
 		;;
+	--invert-exit-code)
+		invert_exit_code=t
+		;;
 	*)
 		echo "error: unknown test option '$opt'" >&2; exit 1 ;;
 	esac
@@ -788,15 +791,31 @@ test_ok_ () {
 	finalize_test_case_output ok "$@"
 }
 
+_invert_exit_code_failure_end_blurb () {
+	say_color warn "# faked up failures as TODO & now exiting with 0 due to --invert-exit-code"
+}
+
 test_failure_ () {
 	failure_label=$1
 	test_failure=$(($test_failure + 1))
-	say_color error "not ok $test_count - $1"
+	local pfx=""
+	if test -n "$invert_exit_code" # && test -n "$HARNESS_ACTIVE"
+	then
+		pfx="# TODO induced breakage (--invert-exit-code):"
+	fi
+	say_color error "not ok $test_count - ${pfx:+$pfx }$1"
 	shift
 	printf '%s\n' "$*" | sed -e 's/^/#	/'
 	if test -n "$immediate"
 	then
 		say_color error "1..$test_count"
+		if test -n "$invert_exit_code"
+		then
+			finalize_test_output
+			_invert_exit_code_failure_end_blurb
+			GIT_EXIT_OK=t
+			exit 0
+		fi
 		_error_exit
 	fi
 	finalize_test_case_output failure "$failure_label" "$@"
@@ -1229,7 +1248,14 @@ test_done () {
 			esac
 		fi
 
-		if test -z "$debug" && test -n "$remove_trash"
+		if test -n "$stress" && test -n "$invert_exit_code"
+		then
+			# We're about to move our "$TRASH_DIRECTORY"
+			# to "$TRASH_DIRECTORY.stress-failed" if
+			# --stress is combined with
+			# --invert-exit-code.
+			say "with --stress and --invert-exit-code we're not removing '$TRASH_DIRECTORY'"
+		elif test -z "$debug" && test -n "$remove_trash"
 		then
 			test -d "$TRASH_DIRECTORY" ||
 			error "Tests passed but trash directory already removed before test cleanup; aborting"
@@ -1242,6 +1268,14 @@ test_done () {
 			} ||
 			error "Tests passed but test cleanup failed; aborting"
 		fi
+
+		if test -z "$skip_all" && test -n "$invert_exit_code"
+		then
+			say_color warn "# faking up non-zero exit with --invert-exit-code"
+			GIT_EXIT_OK=t
+			exit 1
+		fi
+
 		test_at_end_hook_
 
 		GIT_EXIT_OK=t
@@ -1254,6 +1288,13 @@ test_done () {
 			say "1..$test_count"
 		fi
 
+		if test -n "$invert_exit_code"
+		then
+			_invert_exit_code_failure_end_blurb
+			GIT_EXIT_OK=t
+			exit 0
+		fi
+
 		GIT_EXIT_OK=t
 		exit 1 ;;