Is your feature request related to a problem? Please describe.
Upstream work on libc++ happening for security hardening should be adopted.

Describe the solution you'd like
Obvious set of security flags to enable.

The default should be optimal balance; safer than not.

Additional context
https://security.googleblog.com/2024/11/retrofitting-spatial-safety-to-hundreds.html
https://clang.llvm.org/docs/SafeBuffers.html
https://libcxx.llvm.org/Hardening.html
llvm/llvm-project#105863