diff --git a/update_external_sources.sh b/update_external_sources.sh
index 48c77fd..d99f8b9 100755
--- a/update_external_sources.sh
+++ b/update_external_sources.sh
@@ -42,7 +42,11 @@
 function update_LunarGLASS () {
    echo "Updating $BASEDIR/LunarGLASS"
    cd $BASEDIR/LunarGLASS
-   svn update -r "$LUNARGLASS_REVISION"
+   svn update -r "$LUNARGLASS_REVISION" |& tee svnout
+   if grep --quiet LLVM svnout ; then
+      rm -rf $BASEDIR/LunarGLASS/Core/LLVM/llvm-3.4/build
+   fi
+   rm -rf svnout
 }
 
 function build_glslang () {