There does happen to be a research engineer position open at Mozilla right now, but it's for Servo, not Rust. To say nothing of the irony of having Chris Lattner working on Rust while Graydon Hoare works on Swift. :P But hey, Rust could undoubtedly benefit from a full-time LLVM engineer...
From one the presentations of this year's WWDC, I had the impression that there may be some of Rust's ownership concepts incorporated in future versions of Swift. It would definitely be very interesting.
Kotlin is being ported to LLVM, so maybe Google/JetBrains as well?