5:45 PM PT -- Sources close to the production of "Life of Kylie" tell TMZ the lip design in question was independently created by a third party, and Kylie herself had nothing to do with the process.
Kylie Jenner is the Robin Thicke of bleeding lip art ... and one artist is so fed up with KJ's "inspired by" argument that she's taking Jenner to court.
Sara Pope -- an experienced painter whose work has been featured in L.A., Japan, the UK and NYC art galleries -- says Kylie copied her "Temptation Neon" logo and used it to promote a new reality show.
In the docs, obtained by TMZ, Sara says she created her most famous piece of art in 2015 -- a bright, glossy set of lips in a "lip bite" pose. She says Kylie made her own eerily similar graphic, plastered it on social media and used it to promote "Life of Kylie."
Sara says Kylie's got a history of lifting other people's work ... pointing to the infamous Notorious B.I.G./Tupac Shakur t-shirt fiasco and yet another lip artist. She's suing Kylie and NBC Universal ... E!'s parent company.
We've reached out to Kylie's camp and E! ... so far no word back.