Compile issues with this extension

I am having trouble compiling this extension on a Ubuntu 18.04 (current LTS) machine. It appears that the issue has to do with the compile/link instructions in the Makefile. Here is the error message:

usr/bin/install -c -m 644 .//sql/pg_libphonenumber--*.sql '/usr/share/postgresql/11/extension/' /bin/mkdir -p '/usr/lib/postgresql/11/lib/bitcode/pg_libphonenumber' /bin/mkdir -p '/usr/lib/postgresql/11/lib/bitcode'/pg_libphonenumber/src/ /usr/bin/install -c -m 644 src/error_handling.bc '/usr/lib/postgresql/11/lib/bitcode'/pg_libphonenumber/src/ /usr/bin/install -c -m 644 src/pg_libphonenumber.bc '/usr/lib/postgresql/11/lib/bitcode'/pg_libphonenumber/src/ /usr/bin/install -c -m 644 src/packed_phone_number.bc '/usr/lib/postgresql/11/lib/bitcode'/pg_libphonenumber/src/ cd '/usr/lib/postgresql/11/lib/bitcode' && /usr/lib/llvm-6.0/bin/llvm-lto -thinlto -thinlto-action=thinlink -o pg_libphonenumber.index.bc pg_libphonenumber/src/error_handling.bc pg_libphonenumber/src/pg_libphonenumber.bc pg_libphonenumber/src/packed_phone_number.bc error: can't create module summary index for buffer: Expected a single module LLVM ERROR: ThinLink didn't create an index /usr/lib/postgresql/11/lib/pgxs/src/makefiles/pgxs.mk:229: recipe for target 'install' failed make: *** [install] Error 1

I was pointed to a similar error message that had a patch to the Makefile to resolve this issue, but I cannot ufigure out how to apply this technique to this extension