I run OpenBSD 7.8 under an i386 ATOM netbook, n270 CPU and 1GB of RAM.
I hav no Rust, but I have C++, JimTCL, nim (I compled Chawan). Go runs, too.
Maybe I can't compile LLVM in my netbook, but a tuned up machine with 2-4GB of RAM might be able to do such task with a bit of swap in a SSD and boosted up login.conf limits.
Maybe so, but I think it would have to be an amd64 CPU rather than an i386. Maybe you could do it inside of QEMU; does QEMU running on i386 permit emulating address spaces larger than 4GiB?