Can the clang+LLVM toolchain generate a PDB file that can be used by WinDbg? Can it generate .obj and .lib files that can be statically linked with those generated by Visual C++?
You can definitely build obj and lib files and link them with files built by MSVC. That works well.
We also support putting DWARF debug info (the standard format) into the binaries, and the LLVM linker LLD will link them and you can debug the resulting program with the LLVM debugger LLDB (or GDB for that matter).