Dagger is a binary translator to LLVM IR, with the goal of being as native as possible to the LLVM infrastructure.
As an LLVM fork, Dagger is built the same way; assuming you have a reasonably recent toolchain and CMake, just do:
$ cd dagger
$ mkdir build
$ cd build
$ cmake ..
$ make
More information on the llvm.org Getting Started and CMake pages.
While Dagger is intended to be usable as a library, it does come with tools:
llvm-dec takes in an object file and produces IR.
$ ./bin/llvm-dec ./a.out
DYN is an OS X-only dylib that is intended to be preloaded so that it can hijack program execution:
$ echo "int main() { return 42; }" | clang -x c -
$ DYLD_INSERT_LIBRARIES=./lib/libDYN.dylib ./a.out
$ echo $?
42
This will "execute" a.out by translating all of its code to LLVM IR, JITting that, and finally executing it.
The DCDYN_OPTIONS environment variable can be used to pass command-line options. For instance, if you're really brave, you can try:
$ DCDYN_OPTIONS="-print-after-all" DYLD_INSERT_LIBRARIES=build/lib/libDYN.dylib ./a.out
which will print tons of LLVM debug output.
X86 is the main currently supported target. There is ongoing work on adding AArch64 support.
The Mach-O object file format is the best supported. Basic ELF is also supported. However, except for DYN, there is always a generic fallback, so YMMV with other formats.