Using LLVM for build package instead gcc, why not?

[Jonathan MERCIER]

LLVM itself could allow for much greater flexibility in programming
language choice. It can allow for anyone to take any language and output
it in bytecode, machine code, javavm code and so on. If we can rip out
the multitude of compilers on different architectures and replace it
with one compiler base that does many different languages people might
start picking languages based on their merits rather than support (since
it just needs LLVM support to be supported).
If we could swap out old C compilers for a more generic LLVM compiler
for core components like the kernel, userspace libs and so on. In the
future people might just make the decision to move to D since the
architecture is all there and all their old code works but they get all
the new features. Think of Linux distros being built entirely on LLVM.
There are also the other advantages such as dumping in JIT compilers and
automatic threading in LLVM to take advantage of the many processors
systems are starting to get.