We have a winner in the Swoll-Just-Like-My-Dad sweepstakes -- 'cause Arnold Schwarzenegger and Maria Shriver's youngest son Christopher is looking like he could pull it off.

The son of the 7-time Mr. Olympia/5-time Mr. Universe is only 17, but he's obviously growing into his Schwarzenegger genes. Christopher even sported a t-shirt from his dad's bodybuilding competition ... while walking with his mom ... looking more like her bodyguard in L.A.

Fun fact: Arnold won his first Mr. Universe title at age 20. Chris, ya still got a few years to beat Dad's mark.