No rule to make target i686-unknown-linux-gnu/rt/arch/i386/...
While compiling rust with Ubuntu 14.04 on a 32 bits machine with the --llvm-root flag: ... extracting rust-stage0/bin/rustc make: *** No rule to make target `i686-unknown-linux-gnu/rt/arch/i386/morestack.o', needed by `i686-unknown-linux...