This is sphinx tool for llvm use. ! Other zip file except sphinx will be not used, because dot2tex has other packages to rely on. And i also don't use doxygen here, for reason in here https://github.com/llvm/llvm-project/blob/master/llvm/docs/README.txt.
Install doxygen http://www.stack.nl/~dimitri/doxygen/download.html and dot2tex https://dot2tex.readthedocs.io/en/latest.
cd <build-dir>
cmake -DLLVM_ENABLE_DOXYGEN=On <llvm-top-src-dir>
make doxygen-llvm # for LLVM docs
make doxygen-clang # for clang docs
It will generate html in
<build-dir>/docs/doxygen/html # for LLVM docs
<build-dir>/tools/clang/docs/doxygen/html # for clang docs