[mhh__]

Likely never, LLVM IR uses SSA form. This means that optimisations are easier, but the "assembly" is significantly higher lever than assembly a la MIPS. IR is for doing optimisations not executing code (although LLVM does have interpreters if that's what ya need)

[int_19h]

A more interesting question is, when will we see operating systems using LLVM IR (or similar; some future version of WebAssembly, perhaps?) for binaries on disk, dynamically compiling them and caching the result for the current platform as needed.

[mhh__]

In principle that could happen, but LLVM IR is really not designed for anything other than being transformed by LLVM. One could define an abstract risc machine, to be jitted at either side. LLVM is not quite suitable for this purpose: It assumes quite a few details about the target. Also, this requires a huge amount of co-operation. So far this has only happened in the browser with e.g. ECMAScript standardization, asm.js and WebAsm. The JVM tried to do this, but it's not a good compilation target for languages like C/C++. Therefore, I think will happen eventually: The web browsers will develop the tools and specifications to make this stuff, then it will get broken off and used outside of the web (I hope, god forbid all software has to be distributed via the web using overlyHypedWebScale.js v2)

[pjmlp]

iOS 9, ChromeOS PNaCL?

Although it is not really what you are describing.