LLVM doesn't come with the C library headers (VCRuntime) or the executable runtime startup code (VCStartup).Both of which are under Visual Studio proprietary licenses. So to use Clang on Windows without Mingw, you need Visual Studio.

Compared to older Mingw64 environments those link with the latest UCRT so you get almost the same style executable as Visual Studio.

The only difference for C is that it uses Mingw exception handling and global initialization code, and it uses Itanium ABI for C++.