diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 6906a7586ba..7e399fcddd0 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -164,6 +164,7 @@ standard library.
 
 If this error is incorrect or you need to force things to work, you may pass
 '--disable-compiler-version-checks' to configure to bypass this test.])])
+      CXXFLAGS="$llvm_cv_old_cxxflags"
       ;;
     gcc)
       AC_MSG_CHECKING([whether GCC is new enough])
diff --git a/configure b/configure
index b6ccfdb667a..a1b63f88888 100755
--- a/configure
+++ b/configure
@@ -3871,6 +3871,7 @@ fi
 
 rm -f core conftest.err conftest.$ac_objext \
       conftest$ac_exeext conftest.$ac_ext
+      CXXFLAGS="$llvm_cv_old_cxxflags"
       ;;
     gcc)
       { echo "$as_me:$LINENO: checking whether GCC is new enough" >&5
@@ -10660,7 +10661,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10663 "configure"
+#line 10664 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H