https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797
--- Comment #45 from Chris Johns <chrisj at rtems dot org> --- This simple hack as a test works for me with `-j 8` on an i7 without .NOTPARALLEL: --- gcc-7.2.0/libstdc++-v3/include/Makefile.am.orig 2017-10-27 15:30:16.000000000 +1100 +++ gcc-7.2.0/libstdc++-v3/include/Makefile.am 2017-10-27 15:34:00.000000000 +1100 @@ -22,6 +22,8 @@ include $(top_srcdir)/fragment.am +LN_S = cp + # Standard C++ includes. std_srcdir = ${glibcxx_srcdir}/include/std std_builddir = . --- gcc-7.2.0/libstdc++-v3/include/Makefile.in.orig 2017-10-27 15:33:44.000000000 +1100 +++ gcc-7.2.0/libstdc++-v3/include/Makefile.in 2017-10-27 15:34:05.000000000 +1100 @@ -163,7 +163,7 @@ LIBS = @LIBS@ LIBTOOL = @LIBTOOL@ LIPO = @LIPO@ -LN_S = @LN_S@ +LN_S = cp LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@ LTLIBICONV = @LTLIBICONV@ LTLIBOBJS = @LTLIBOBJS@ In terms of make I would expect `cp` and `ln -s` to be the same. Maybe Apple would like to help out?