Can't wait until Apple will disclose more information about Swift IR that compiles to LLVM IR. Too bad they canceled this year LLVM Devmeeting keynote.
SIL has a very large number of differences from LLVM IR. It's essentially built as an IR that the can do static analysis and high level optimization on.
This means it has a number of higher level constructs that LLVM doesn't, in order to be able to achieve the semantics they want for static analysis, and in order to be able to do things like optimize dispatch.
If you want to look at something similar, OpenCL has an LLVM IR -based standardized binary IR.