Also to note, LLVM isn't the first compiler toolchain of its kind.

Notable mentions,

IBM's research project on PL.8 while developing their first RISC designs.

https://rsim.cs.uiuc.edu/arch/qual_papers/compilers/auslande...

https://pdfs.semanticscholar.org/3288/fc042cd474f0ec93d67753...

https://rishiheerasing.net/modules/hca2102/paper/cocke.pdf

The Amsterdam Compiler Toolkit,

http://tack.sourceforge.net/

https://github.com/davidgiven/ack

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.12...

The more the merrier.