One thing I want to comment on here is a mistake I often make myself, which is to focus on the language/compiler/interpreter/jit/translators/etc. and to loose sight of the platform APIs -- user interfaces, input devices, OS services, data sources, and so on. As fun as it is to talk about languages on HN, APIs are arguably a bigger part of the big picture in many platforms. LLVM itself doesn't come with any platform APIs, so it's typically just one part in a larger and much more complex system.