ac_add_options BINDGEN_CFLAGS="$(pkg-config nspr pixman-1 --cflags)"
EOF
-%{!?with_clang:export MOZ_MAKE_FLAGS="-j1"}
+# On x86_64 architectures, Mozilla can build up to 4 jobs at once in parallel,
+# however builds tend to fail on other arches when building in parallel.
+RPM_BUILD_NR_THREADS=$(echo %{_smp_mflags} | cut -dj -f2)
+%ifarch %{x8864}
+[ -n "RPM_BUILD_NR_THREADS" -a "$RPM_BUILD_NR_THREADS" -gt 4 ] && RPM_BUILD_NR_THREADS=4
+%else
+RPM_BUILD_NR_THREADS=1
+%endif
+export MOZ_MAKE_FLAGS="-j${RPM_BUILD_NR_THREADS}"
+
export MOZ_SERVICES_SYNC="1"
%if %{with pgo}
D=$(( RANDOM % (200 - 100 + 1 ) + 5 ))