PNaCl's LLVM IR is machine independent and can be used standalone without Chrome.

While true in a narrow sense, it does so by targeting the lowest common practical denominator—in practice, a chip that looks a lot like a 386 or 32-bit ARM with no SIMD pipeline. That puts it as little more than a better GNU Lightning.

It has SIMD: https://developer.chrome.com/native-client/reference/pnacl-c...