New York rapper Lil Peep, whose lyrics were laced with drug references, has died of a suspected overdose on his tour bus ... TMZ has confirmed.

Lil Peep's body was found on the bus Wednesday night outside a club called The Rock in Tucson. He was scheduled to perform there. Law enforcement tells us his manager went to check on him around 8:50 PM and found him dead. We're told there was drug paraphernalia around him, and evidence of a possible overdose, and it was likely he'd taken Xanax.

Peep had posted a photo earlier in the day with what appeared to be prescription pills on his tongue and the caption, "fucc it."

Peep was an up-and-comer whose emo lyrics -- sometimes rapped, sometimes sung -- attracted several celebs in and out of the music biz. He and Bella Thorne had hooked up back in September.

Post Malone immediately reacted to his death on social media.

in the short time that i knew you, you were a great friend to me and a great person. your music changed the world and it'll never be the same. i love you bud. forever pic.twitter.com/tpbxpkf4f4

DJ Marshmello had toured with Peep, and said they'd just been talking about doing music together.

Peep was the nicest person. hanging out with him, talking to him about music, the song ideas we were going to do together and touring was so amazing. Everyone will miss you man @Lilpeep

Peep, whose real name was Gustav Ahr, had just released his debut album, "Come Over When You're Sober (Part One)" in August.

He was just 21.