I'm very confused what magic you believe will achieve what has not so far been achieved.
I'm also confused why you believe LLVM didn't start out the exact same way?
I say this as one of the main people responsible for working on combined pass replacements in both GCC and LLVM for things that were reasonable to be combined.
I actually love destroying lots of passes in favor of better combined ones. In that sense, i'm the biggest fan in the world of these kinds of efforts.
But the reason these passes exist is not cruft, or 20 years of laziness, - it's because it's very hard to replace them with combined algorithms that are both faster, and achieve the same results.
What exactly do you plan on replacing GVN + Simplify CFG + Jump Threading + correlated value prop with?
It took years of cherrypicking research and significant algorithm development to develop algorithms for this that had reasonable timebounds, were faster, and could do better than all of them combined. The algorithm is quite complex, and it's hard to prove it terminates in all cases, actually. The number of people who understand it is pretty small because of the complexity. That's before you get to applied engineering of putting it in a production compiler.
These days, as the person originally responsible for it, i'd say it's not better enough for the complexity, even though it is definitely faster and more complete and would let you replace these passes.
Meanwhile, you seem to think you will mature everything and get there in a few years.
I could believe you will achieve some percent of GCC or LLVM's performance, but that's not the reason these passes exist. They exist because that is what it reasonably takes to achieve LLVM (and GCC's) performance across a wide variety of code, for some acceptable level of algorithm complexity and maintainability.
So if you told me you were only shooting for 80% across some particular subset code, i could believe 10-20 passes.
If you told me you were going to build a different product that targets a different audience, or in a different way, i could maybe believe it.
But for what you say here, I think you vastly underestimate the difficult and vastly underappreciate the effort that goes into these things. This is hundreds of very smart people working on things for decades.
It's one thing to have a healthy disrespect for the impossible.
It's another to think you will, in a few years, outdo hundreds of smart, capable engineers on pure technical achievement.
That strikes me as somewhere between hubris and insanity.
People also pretty much stopped building and publishing general purpose compiler optimization algorithms a decade ago, moving towards much more specialized algorithms and ML focused things and whatnot.
This is because in large part, there isn't a lot left worth doing.
So unless you've got magic bullets nobody else has, either you won't achieve the same performance level, or it will be slow, or it will take you a significant amount of algorithm development and engineering well beyond "a few years".
I say this not to dissuade you, but to temper your apparent expectations and view.
Honestly - I wish you the best of luck, and hope you succeed at it.