Kylie Jenner -- Calm Down, Internet ... It's Just a Push-Up Bra

Kylie Jenner is scoffing at reports she got a boob job ... she's saying her busty Instagram photo is just the work of a fancy bra.

Our Kardashians sources say Kylie bought a new Victoria's Secret bra -- called Bombshell -- which increases your bust by 2 cup sizes. It's the bra Taylor Swift wore at the Victoria's Secret Fashion Show.

There are reports Bruce is upset over Kris allowing Kylie to get plastic surgery, but it's not true because she didn't go under the knife.

And, we're told Kris, Kim, Khloe and Kourtney thought the bra made Kylie look so good they ordered some for themselves.