Currently, every time we roll the new Clang toolchain, there's a chance that a regression has been introduced and that the official Chrome link time would become 2x larger.

In order to see if that's the case and also to detect possible future regressions early, we need to setup a bot that builds Chromium with CFI/LTO and measures link time.

Technically, this can be done as a separate step similar to sizes step here:
https://build.chromium.org/p/chromium.perf/builders/Linux%20Builder/builds/50301
and just look into the ninja logs. Here is the potential command line:

$ cat .ninja_log | grep -P '\tchrome\t' | tail -n1 | awk '{print ($2-$1)/60000 " mins"}'                                      
29.3973 mins

The bot that measures the link time shall not run any tests. Otherwise, the results will vary drastically (up to 2x) as observed on build.chromium.org/p/chromium.fyi/builders/LTO Linux

It's a nice to have, not must to have feature request to myself.