diff --git a/configure.ac b/configure.ac
index d160633c6e..5049d9e96b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -114,6 +114,9 @@ AM_CONDITIONAL([USE_EXTERNAL_PROTOC], [test "$with_protoc" != "no"])
 ACX_PTHREAD
 AC_CXX_STL_HASH
 
+# HACK:  Make gtest's configure script pick up our copy of CXXFLAGS, since the
+#   flags added by ACX_CHECK_SUNCC must be used when compiling gtest too.
+export CXXFLAGS
 AC_CONFIG_SUBDIRS([gtest])
 
 AC_CONFIG_FILES([Makefile src/Makefile protobuf.pc protobuf-lite.pc])