Build error for llvm 8.0.0

I have been building llvm 8.0.0 as a cross compiler for the AROS operating system and have been stuck with this error:

– Installing: /home/ridgeone/builds/aros2-bld8-clang22d/bin/linux-x86_64/tools/crosstools/lib/
– Installing: /home/ridgeone/builds/aros2-bld8-clang22d/bin/linux-x86_64/tools/crosstools/lib/
– Installing: /usr/lib/ocaml/llvm/llvm.mli
CMake Error at bindings/ocaml/llvm/cmake_install.cmake:49 (file):
file INSTALL cannot copy file
to “/usr/lib/ocaml/llvm/llvm.mli”.
Call Stack (most recent call first):
bindings/ocaml/cmake_install.cmake:42 (include)
cmake_install.cmake:67 (include)

mmakefile:346: recipe for target ‘/home/ridgeone/builds/aros2-bld8-clang22d/bin/linux-x86_64/gen/host/tools/crosstools/llvm/llvm/.installed’ failed
make[1]: *** [/home/ridgeone/builds/aros2-bld8-clang22d/bin/linux-x86_64/gen/host/tools/crosstools/llvm/llvm/.installed] Error 1
[MMAKE] Error: Error while running make in tools/crosstools/llvm: No such file or directory

llvm is the second program built bythe compiler llvm 8 for this project.

Why is it failing?

What log or error files should I be looking at with an llvm build?

Why is llvm (cmake) writing back the files it copied from my system?
Are write permissions really necessary to let llvm (cmake) write back these files?

Thank you for any help!