Won't that increase memory usage since the rosegment will no longer be shared across processes? Does lld not support this option? 

+cc vapier

no, the default for gold is -no-rosegment and that is what is currently used.

We tried to use -rosegment a while back and it broke breakpad (crash dumps).
There is a fix for that issue now but we want to be conservative and enable 
LLD first and then -rosegment

breakpad fix: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/513610

I got a broken Chrome when adding -no-rosegment to lld on AMD64 board. Not sure whether it is still the case now. 

I've run some tryjobs with a CL that adds -no-rosegment to LLD builds: nautilus & veyron_jaq succeeded completely (Building & running HW tests).  My Kevin build had some issues, so I'm re-running it to see whether the issues were flaky or real.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/cd8d110dd3faf87c12a0bdaf471522170aaecdd6

commit cd8d110dd3faf87c12a0bdaf471522170aaecdd6
Author: Caroline Tice <cmtice@google.com>
Date: Tue Dec 11 00:00:34 2018

chromeos-chrome: Migrate Chrome to LLD.

This CL changes the default linker for Chrome from gold
to LLD.

BUG= chromium:909853 ,  chromium:701659 
TEST=LLD has been extensively tested with Chrome in ChromeOS.

See this testing matrix for details:
https://docs.google.com/spreadsheets/d/13uSAfC82BVIagEtp-jgIABKDA6HihjgrKxqBBQXPWDU/edit?ts=5bfdd752#gid=0

Change-Id: I23f52de37fdbd8fadce1de48730601e124b90d6b
Reviewed-on: https://chromium-review.googlesource.com/1354161
Commit-Ready: Caroline Tice <cmtice@chromium.org>
Tested-by: Caroline Tice <cmtice@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>

[modify] https://crrev.com/cd8d110dd3faf87c12a0bdaf471522170aaecdd6/chromeos-base/chromeos-chrome/chromeos-chrome-9999.ebuild

Disabling rosegment causes ARM boards to fail nondeterministically.  Leaving it enabled is fine: Have verified that crash backtraces are properly symbolized.