Index: libcxx/include/streambuf
===================================================================
--- libcxx/include/streambuf
+++ libcxx/include/streambuf
@@ -281,7 +281,9 @@
     // 27.6.2.4.3 Get area:
     virtual streamsize showmanyc();
     virtual streamsize xsgetn(char_type* __s, streamsize __n);
+    inline _LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY
     virtual int_type underflow();
+    inline _LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY
     virtual int_type uflow();
 
     // 27.6.2.4.4 Putback: