I'm writing a compiler for a C-like language, currently called T (although there does exist another language of that name, so I'm probably going to rename the language at some point).
The compiler itself is written in C, and targets x86_64 directly (not using LLVM). It's eventually going to be self-hosting, but at the moment I'm slogging through assembly generation. I can see why most modern production compilers target LLVM. (GCC, being older than LLVM, of course uses its own backend.)