While this section is not strictly needed for modern systems there are a lot of linux-arm devices out there with older glibc and eglibc which both require that this section is part of a shared object in order to dlopen it.
Peter Smith did a similar patch against lld a couple of years ago:
There is more context and discussion on llvm-dev: http://lists.llvm.org/pipermail/llvm-dev/2019-October/135993.html
This is my first contribution to LLVM - so please let me know if I did something wrong. I am mostly unsure about how I did the test for this bug.This works around a bug in Ubuntu and Debian's patchset for glibc. The bug is described in detail in the upstream launchpad bug: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1712938, But I was able to confirm that it fails without my patch, and passes with it. but the short version of it is that glibc on Ubuntu/Debian don't load libraries unless it has a .ARM.attribute section.