You said that if I have to install GCC, you might as well just use it for everything. That statement very clearly doesn't apply anymore, since it's binutils that's the dependency. Or if you still stand by it, it means that you consider GCC to also be "incomplete".
How do I get the necessary binutils on Windoze? Install MinGW or Cygwin. But if I do that, then I may as well use MinGW for everything and not bother with LLVM.
Our frontend compiler can generate C code as input to a C compiler (such as GCC in MinGW) and use the C compiler as a backend solution. Alternatively our frontend compiler could be made to generate LLVM instructions as input to LLVM. The problem is that LLVM is an incomplete backend solution -- LLVM practically requires that MinGW or Cygwin be installed.
But if MinGW or Cygwin is installed, then I have no need for LLVM !!
So the point is, Windoze developers will tend to reject LLVM while it requires that MinGW or Cygwin be installed, because MinGW/Cygwin eliminate the need for LLVM.
Make LLVM usable as a DLL or SLL in Windoze, capable of generating a finished ready-to-execute .EXE or .DLL file, without requiring that MinGW or Cygwin be installed first.