I don’t think that changing the meaning of align to no longer mean “minimum alignment” as done in CodeGen: Respect function align attribute if less than preferred alignment. by pcc · Pull Request #149444 · llvm/llvm-project · GitHub is appropriate. The meaning of align (on allocations/objects) everywhere in LLVM is a minimum alignment, which can be increased if considered profitable.
If you want to introduce a separate preferred alignment property, the way to do it is to leave align alone and add a separate prefalign. Not to change the meaning of align and add minalign.