When lldb loads a binary that was built -fsanitize=address, it prints an info message via the Module's warning printer; it looks like
warning: (x86_64h) /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/lib/darwin/libclang_rt.asan_osx_dynamic.dylib AddressSanitizer debugger support is active. Memory error breakpoint has been installed and you can now use the 'memory history' command.
Instead, I think we should grab the debugger's output stream and print the message there without the warning/arch/module name. Like
AddressSanitizer debugger support is active. Memory error breakpoint has been installed and you can now use the 'memory history' command.