(please keep these discussions on-list for the benefit of others)
As long as you build the ARM back-end for LLVM and have an ARM sysroot on your x86 machine, you can use Clang on the x86 machine to compile ARM binaries. I've only played around with this a few times, but I was able to build hard-float ARM binaries on an x64 Linux host and run them on a Panda Board running Arch Linux.
This worked for my simple cases. If you need C++, you'll have to obtain an ARM libstdc++ and probably use -sysroot to specify the system include/lib paths. This goes beyond my experience for this setup, however, so someone else will have to chime in here.