diff -rauN a/mozconfig b/mozconfig
--- a/mozconfig	2019-10-25 16:52:15.320214766 +0200
+++ b/mozconfig	2019-10-25 16:52:51.400721588 +0200
@@ -5,11 +5,12 @@
 ac_add_options --enable-hardening
 ac_add_options --enable-optimize
 ac_add_options --enable-rust-simd
-export CC='clang --target=x86_64-unknown-linux-gnu'
-export CXX='clang++ --target=x86_64-unknown-linux-gnu'
-export AR=llvm-ar
-export NM=llvm-nm
-export RANLIB=llvm-ranlib
+ac_add_options --disable-lto
+export CC=gcc
+export CXX=g++
+export AR=gcc-ar
+export NM=gcc-nm
+export RANLIB=gcc-ranlib
 
 # Branding
 ac_add_options --enable-official-branding
@@ -38,3 +39,6 @@
 ac_add_options --disable-gconf
 ac_add_options --disable-updater
 ac_add_options --disable-tests
+
+# disable PGO
+ac_add_options --disable-cross-pgo