Kylie Jenner Shows Off Killer Bikini Body in New Selfie

Kylie Jenner rocks a tiny black bikini while posing in front of her mirror in this new Instagram photo.

The 17-year-old reality star took a dip in the pool to cool off that day with her older sister Kourtney Kardashian, 36.

PHOTOS: Check out the latest pics of Kylie Jenner

“Kourt & Ky swim session,” she captioned the photo.

In case you missed it, Kylie is gearing up for her big 18th birthday on August 10 where she will be celebrating by hosting a party in Montreal, Canada.

FYI: Kylie is wearing a Bravura bikini.