WebAssembly LLVM Backend Being Discussed
A WebAssembly back-end has been proposed for LLVM. WebAssembly is a new virtual ISA designed to run compiled code within web browsers.
WebAssembly is a new virtual ISA initially for programming in C/C++ to then target modern, cross-platform web browsers. This virtual ISA is optimized for reduced download sizes, strong portability and predictability invariants, and is to be supported by multiple web browsers.
The actual LLVM back-end for WebAssembly has yet to actually materialize but is currently being discussed for how it will be developed. The WebAssembly developers would ideally like to develop this experimental back-end from scratch within the LLVM tree and so far that's been reasonably approved by upstream LLVM developers.
Those wishing to learn more about WebAssembly can visit their GitHub project page while details on their LLVM plans can be found via this mailing list thread.