I earlier posted regarding junior level llvm positions at MIPS.
I had a typo in my email in case anyone had trouble sending.
Senior is possible . It's a small team and we have fun things we all work on but we also have to all pitch in on less exciting tasks for a senior level person. That is the main reason for the "junior" adjective. So you could get tasked to spend time helping to beef up the test suite or there might be an emergency and we all have to work on some area of the compiler that is not particularly interesting or challenging for a senior person to work on. So for a junior level person, all these tasks would teach them more about building production compilers and making products. For someone that only wants to work on cutting edge optimization algorithms; the position might not be to their liking.