GNU strip supports both -s and -S as aliases for --strip-all and --strip-debug, respectfully.
As part of this, it turns out that strip/objcopy were accepting case insensitive command line args. I'm not sure if there was an explicit reason for this. The only others uses of this are llvm-cvtres/llvm-mt/llvm-lib, which are all tools specific for windows support. Forcing case sensitivity allows both aliases to exist, but seems like a good idea anyway.
And as a surprise test case adjustment, the llvm-strip unit test was running with -keep=unavailable_symbol, despite keep not be a valid flag for strip. This is because there is a flag -K which, when case insensitivity is permitted, allows it to be interpreted as -K = eep=unavailable_symbol (e.g. to allow -Kfoo == --keep-symbol=foo).