Use compiled LLVM/clang without gcc

Question

I have been trying to compile LLVM/clang from source, both by myself and using this script. I am compiling clang using gcc 11.2, which itself was also built from source, and hence resides in a non-default location on my system (/scratch/opt/gcc-ml-11.2). Note that it only works with a gcc that was compiled with multilib enabled.

The problem is that I can use the compiled clang and clang++ binaries only if I supply the gcc location as follows: --gcc-toolchain=/scratch/opt/gcc-ml-11.2.0. Without that flag, I run into linker errors:

clang test.c -o test
/usr/bin/ld: cannot find crtbeginS.o: No such file or directory
/usr/bin/ld: cannot find -lgcc
/usr/bin/ld: cannot find -lgcc_s

I do not understand why a clang compiled binary needs to link against some kind of gcc library and why clang does not supply the crtbeginS.O file.

I have also tried using the LLVM linker as well as the LLVM standard library for C++ test applications, i.e., "-fuse-ld=lld -stdlib=libc++. This did not help either.

While I could just export CXXFLAGS=--gcc-toolchain=/scratch/opt/gcc-ml-11.2.0, I am not sure whether this is the right approach. Shouldn't clang/LLVM be able to function without a gcc installation?

I have also tried using my clang installation with the --gcc-toolchain=/scratch/opt/gcc-ml-11.2.0 flag to compile clang again, but the new binary also requires the gcc-toolchain flag.

Should I just globally export the path to my gcc toolchain? Why is this necessary? Isn't clang a standalone compiler that - if supplied with the option to use its own standard library - does not require gcc?

Thank you very much for your help!

Best, Maxbit