It works with optimized builds, and it works better with them than gdb does.

When you debug an optimized build with debug info in gdb by stepping line by line, it is easy to accidentally step "too far" and completely lose your place. In rr, you can always step back and recover.

You might be relegated to stepping through disassembled machine code. I was able to use rr with a home made JIT compiler, stepping through JIT’d instructions. So I see no reason why you can’t at least get that experience with a production binary.