Why does `opt` not infer the data-layout based on the triple?

Hi all,

I’ve hit the curious case of wondering why `opt` seemingly does not
infer the datalayout, from the passed `-mtriple`?

All I can see from the source is that opt defaults to the default
data layout if none is specified in the ir file, or provided via
`-[default-]data-layout=`.

Is there a reason that the data-layout is not inferred from the triple?

Cheers,
Moritz