diff --git a/gcc/configure b/gcc/configure
index d21b33e2b6c..e7f85b78ad9 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -5477,8 +5477,8 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
 # optimizations to be activated explicitly by the toplevel.
 case "$CC" in
   */prev-gcc/xgcc*) ;;
-  *) 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]*[ 	]//" ` ;;
+  *) 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
 
 
diff --git a/gcc/configure.ac b/gcc/configure.ac
index b1b21cf4d7b..a6c650c8f3a 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -467,8 +467,8 @@ AC_LANG(C++)
 # optimizations to be activated explicitly by the toplevel.
 case "$CC" in
   */prev-gcc/xgcc*) ;;
-  *) CFLAGS=`echo "$CFLAGS " | sed -e "s/-Ofast[[ 	]]//" -e "s/-O[[gs]][[ 	]]//" -e "s/-O[[0-9]]*[[ 	]]//" `
-     CXXFLAGS=`echo "$CXXFLAGS " | sed -e "s/-Ofast[[ 	]]//" -e "s/-O[[gs]][[ 	]]//" -e "s/-O[[0-9]]*[[ 	]]//" ` ;;
+  *) CFLAGS=`echo "$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)