--- gcc/configure.ac.jj	2012-09-13 18:29:46.000000000 +0200
+++ gcc/configure.ac	2012-09-24 21:47:41.606278259 +0200
@@ -296,8 +296,8 @@ AC_SUBST(OUTPUT_OPTION)
 # optimizations to be activated explicitly by the toplevel.
 case "$CC" in
   */prev-gcc/xgcc*) ;;
-  *) CFLAGS=`echo $CFLAGS | sed "s/-O[[s0-9]]* *//" `
-     CXXFLAGS=`echo $CXXFLAGS | sed "s/-O[[s0-9]]* *//" ` ;;
+  *) CFLAGS=`echo "$CFLAGS " | sed -e "s/-Ofast[[ 	]]//" -e "s/-O[[gs]][[ 	]]//" -e "s/-O[[0-9]]*[[ 	]]//" `
+     CXXFLAGS=`echo "$CXXFLAGS " | sed -e "s/-Ofast[[ 	]]//" -e "s/-O[[gs]][[ 	]]//" -e "s/-O[[0-9]]*[[ 	]]//" ` ;;
 esac
 AC_SUBST(CFLAGS)
 AC_SUBST(CXXFLAGS)
--- gcc/configure.jj	2012-09-17 11:13:13.119075354 +0200
+++ gcc/configure	2012-09-24 21:49:02.900837573 +0200
@@ -4863,8 +4863,8 @@ fi
 # optimizations to be activated explicitly by the toplevel.
 case "$CC" in
   */prev-gcc/xgcc*) ;;
-  *) CFLAGS=`echo $CFLAGS | sed "s/-O[s0-9]* *//" `
-     CXXFLAGS=`echo $CXXFLAGS | sed "s/-O[s0-9]* *//" ` ;;
+  *) CFLAGS=`echo "$CFLAGS " | sed -e "s/-Ofast[ 	]//" -e "s/-O[gs][ 	]//" -e "s/-O[0-9]*[ 	]//" `
+     CXXFLAGS=`echo "$CXXFLAGS " | sed -e "s/-Ofast[ 	]//" -e "s/-O[gs][ 	]//" -e "s/-O[0-9]*[ 	]//" ` ;;
 esac