diff --git a/cc/config/global.go b/cc/config/global.go
index a40f5eadf..26d93abb3 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -375,6 +375,10 @@ func init() {
 			flags = append(flags, llvmNextExtraCommonGlobalCflags...)
 		}
 
+		if ctx.Config().IsEnvTrue("ALLOW_UNKNOWN_WARNING_OPTION") {
+			flags = append(flags, "-Wno-error=unknown-warning-option")
+		}
+
 		return strings.Join(flags, " ")
 	})