+OPTS="--depth 10000"
+%if !0%{?rhel:1} || 0%{?rhel} > 7
+ OPTS="$OPTS --no-tags"
+%endif
+REF="reference"
+# RHEL-7 does not support: --reference-if-able
+CLONEOPTS="--single-branch"
+test -d ../$REF/ && CLONEOPTS="$CLONEOPTS --reference ../$REF"
+# 2500 = 1 month in 2019
+git clone $OPTS $CLONEOPTS https://github.com/llvm/llvm-project.git .