When I try to build Firefox with "ac_add_options --enable-linker=lld" in my ./mozconfig file (using clang 4.0 and lld 4.0), it fails with: 22:15.33 libxul_s.a.desc 22:15.33 libxul.so 22:43.86 libtestcrasher.soplugin-container 22:43.86 22:44.05 xpcshell 22:46.38 css_properties.js 22:46.82 dependentlibs.list 22:48.47 native-addon-test.xpi 22:48.47 native-overrides-test.xpi 22:48.54 collection_signing_root.pem 22:48.54 collection_signing_int.pem 22:48.77 collection_signing_ee.pem 22:54.06 === 22:54.06 === If you get failures below, please file a bug describing the error 22:54.07 === and your environment (compiler and linker versions), and 22:54.08 === provide the pre-elfhacked library as an attachment. 22:54.08 === Use --disable-elf-hack until this is fixed. 22:54.08 === 22:54.09 === If you get failures below, please file a bug describing the error 22:54.09 === 22:54.09 === and your environment (compiler and linker versions), and 22:54.10 === provide the pre-elfhacked library as an attachment. 22:54.10 === Use --disable-elf-hack until this is fixed. 22:54.11 0x0000000000000019 (INIT_ARRAY) 0xb000 22:54.11 === 22:54.13 0x000000000000000c (INIT) 0x8030 22:54.14 test-array.so: Reduced by 8440 bytes 22:54.14 test-ctors.so: Reduced by 8400 bytes 22:54.22 Segmentation fault 22:54.22 Makefile:51: recipe for target 'libs' failed 22:54.22 make[5]: *** [libs] Error 139 22:54.22 /home/user/firefox/config/recurse.mk:100: recipe for target 'build/unix/elfhack/libs' failed 22:54.22 make[4]: *** [build/unix/elfhack/libs] Error 2 22:54.23 /home/user/firefox/config/recurse.mk:32: recipe for target 'libs' failed 22:54.23 make[3]: *** [libs] Error 2 22:54.23 /home/user/firefox/config/rules.mk:453: recipe for target 'default' failed 22:54.23 make[2]: *** [default] Error 2 22:54.23 /home/user/firefox/client.mk:424: recipe for target 'realbuild' failed 22:54.23 make[1]: *** [realbuild] Error 2 22:54.23 client.mk:175: recipe for target 'build' failed 22:54.23 make: *** [build] Error 2 22:54.27 316 compiler warnings present. 22:54.61 ccache (direct) hit rate: 55.9%; (preprocessed) hit rate: 20.1%; miss rate: 24.0% I'm not sure which "pre-elfhacked library" I should attach. My "obj-x86_64-pc-linux-gnu/build/unix/elfhack/" folder contains: Makefile dummy.o host_elf.o test-array.o test-array.sotmp197cb685 test-ctors.so.bak backend.mk dummytmpe89a57a5 host_elfhack.o test-array.so test-ctors.o test-ctors.sotmpcfa67127 dummy elfhack inject/ test-array.so.bak test-ctors.so

FYI the lld build works again when I add "ac_add_options --disable-elf-hack" to my ./mozconfig file.