I think you have already read it in the news. But I think it needs also a place here, to remember for later times.
Ceemple Software Ltd.have published a modified clang as OpenSource for x86 Linux
https://www.zapcc.com/
https://github.com/yrnkrn/zapcc
So it would be a long time project, to port it to Haiku.
But the benefit you can see at
https://www.zapcc.com/demo-webkit/
https://www.zapcc.com/demo-incremental-build/
So possibly it would also be faster to compile and recompile Haiku.