Guitar legend Tom Morello is pissed ... telling TMZ Sports he's sick and tired of the Chicago Cubs perennially sucking ass -- especially because the future doesn't look bright either.
Morello -- a founding member of Rage Against the Machine -- grew up in Chi-town and says it makes him sick to his stomach that his Cubbies are having yet another terrible season ... but it's par for the course.
FYI -- the Cubs lost AGAIN last night ... bringing their record to an abysmal 19-32.
Hey, at least they're renovating Wrigley Field soon. So, there's that.