Angelina Jolie was apparently responsible for breaking the news about her relationship with Brad Pitt, according to the founder of Rolling Stone magazine … who attributes her for getting the bombshell shots back in 2005.

Jann Wenner‘s upcoming memoir, ‘Like a Rolling Stone,’ is full of stories about the celebs he’s encountered over the years, according to Page Six … but this one might take the cake, putting to bed a 17-year mystery on who first blabbed about Brangelina.

Jann owned Us Weekly when rumors were flying about BP and AJ being an item … when their photographer got a tip about the two staying at a resort on the coast of Africa.

He puts it plainly — “the tipster was Angelina.” Of course, this was all going down while Brad was still married to Jennifer Aniston.

Not only did Jann’s photog know where to find them, but Angelina gave specific details about their daily walks, and even where they could secretly snag a pic of them.

Jann says they finally got the proof after Angelina’s tip … adding “we had the worldwide scoop, the debut of Brangelina.”