cd $(dirname $0)
TOP=$PWD
-ln -sf ../../clang llvm/tools/clang
-mkdir -p llvm/_build
-cd llvm/_build
-../configure --prefix=$TOP/_install
-
-cat <<EOF
-To compile LLVM run the following comands:
-cd $PWD
-make install
+if [ -x llvm/configure ]; then
+ echo "Will build llvm and clang from sources"
+ ln -sf ../../clang llvm/tools/clang
+ mkdir -p llvm/_build
+ (
+ cd llvm/_build
+ ../configure --prefix=$TOP/_install --enable-optimized
+ )
+ LLVM_CONFIG=$TOP/_install/bin/llvm-config
+else
+ echo "Using system-wide llvm and clang"
+ LLVM_CONFIG=llvm-config
+fi
+
+cat <<EOF > $TOP/Makefile.config
+LLVM_CONFIG := $LLVM_CONFIG
EOF
+
+echo "Now run make to compile everything"