Kylie Jenner Flashes Serious Cleavage In Push-Up Bra & Mesh Shirt at Kendall's B-Day Bash

The 19-year-old reality star rocked a seriously dramatic look in celebration of Kendall Jenner's 21st birthday ... and while Kenny looked amazing, all eyes were on her baby sis.

The duo and their crew headed to L.A.'s latest hotspot, Delilah, where the rest of the Kardashians — sans Kim — were in attendance.

Kylie wore a black, high-necked, long-sleeved mesh top over a black lace push-up bra, and continued her gothic look by pairing it with lace-up leather pants and gemstone-encrusted strappy heels.

She wore her platinum locks long and loose, with minimal makeup and a pink manicure. Even her jewelry was minimal — perhaps taking a page out of sister Kim's book — and she sported a diamond choker, watch, and a few rings.

The birthday girl, on the other hand, wore a very revealing sequined silver sheath dress, and paired it with a matching silver manicure and nude heels. She wore her hair in loose waves and also opted for minimal makeup.

She was also spotted in a sheer, lace-up black bodysuit for dinner before the party.

Kourtney and Khloe were seen at the Delilah soiree as well, both showing some leg in a pair of minis.

The real question of the matter, though, is "Who did Kendall Jenner's birthday best?"