get maximum alignment size needed?

Is there a standard way to get the maximum alignment needed by any type
for the target platform? I use the TargetData class to get individual
type alignments/sizes, but I don't see a function for target maximum.

I'm just trying to pack two structures together in memory, one following
the other. The offset to the second one should be constant (not
depending on its type), thus I'd like to figure out what the maximum
alignment for the platform is. That is, C++'s max_align_t.