GNU objcopy accepts the --wildcard flag to allow wildcard matching on symbol-related flags. (Note: it's implicitly true for section flags).
The basic syntax is to allow *, ?, \, and  which work similarly to how they work in a shell. Additionally, starting a wildcard with ! causes that wildcard to prevent it from matching a flag.
Instead of writing a new regex class, add a helper to llvm's Regex that translates a wildcard syntax into a general regular expression.