diff --git a/t/README b/t/README
index 70841a4645b2469d8263553a7ba41d4f953774f7..dc892631e00c16ef1477b8ab9b157a27dece91fe 100644
--- a/t/README
+++ b/t/README
@@ -54,6 +54,10 @@ You can pass --verbose (or -v), --debug (or -d), and --immediate
 	This causes the test to immediately exit upon the first
 	failed test.
 
+--long-tests::
+	This causes additional long-running tests to be run (where
+	available), for more exhaustive testing.
+
 
 Naming Tests
 ------------
diff --git a/t/test-lib.sh b/t/test-lib.sh
index c861141667eb03eb42f559cbe174c6a76dd704c9..e331cadcff479a8d9de59590c44b0502653653f9 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -80,6 +80,8 @@ do
 		debug=t; shift ;;
 	-i|--i|--im|--imm|--imme|--immed|--immedi|--immedia|--immediat|--immediate)
 		immediate=t; shift ;;
+	-l|--l|--lo|--lon|--long|--long-|--long-t|--long-te|--long-tes|--long-test|--long-tests)
+		export GIT_TEST_LONG=t; shift ;;
 	-h|--h|--he|--hel|--help)
 		help=t; shift ;;
 	-v|--v|--ve|--ver|--verb|--verbo|--verbos|--verbose)