Index: lto-streamer-out.c
===================================================================
--- lto-streamer-out.c	(revision 214085)
+++ lto-streamer-out.c	(working copy)
@@ -648,9 +648,13 @@ DFS::DFS_write_tree_body (struct output_
   if (CODE_CONTAINS_STRUCT (code, TS_BLOCK))
     {
       for (tree t = BLOCK_VARS (expr); t; t = TREE_CHAIN (t))
-	/* ???  FIXME.  See also streamer_write_chain.  */
-	if (!(VAR_OR_FUNCTION_DECL_P (t)
-	      && DECL_EXTERNAL (t)))
+	if (VAR_OR_FUNCTION_DECL_P (t)
+	    && DECL_EXTERNAL (t))
+	  /* We have to stream externals in the block chain as
+	     non-references.  See also
+	     tree-streamer-out.c:streamer_write_chain.  */
+	  DFS_write_tree (ob, expr_state, t, ref_p, false, single_p);
+	else
 	  DFS_follow_tree_edge (t);
 
       DFS_follow_tree_edge (BLOCK_SUPERCONTEXT (expr));
Index: tree-streamer-out.c
===================================================================
--- tree-streamer-out.c	(revision 214085)
+++ tree-streamer-out.c	(working copy)
@@ -524,11 +524,11 @@ streamer_write_chain (struct output_bloc
       /* We avoid outputting external vars or functions by reference
 	 to the global decls section as we do not want to have them
 	 enter decl merging.  This is, of course, only for the call
-	 for streaming BLOCK_VARS, but other callers are safe.  */
-      /* ???  FIXME wrt SCC streaming.  Drop these for now.  */
+	 for streaming BLOCK_VARS, but other callers are safe.
+	 See also lto-streamer-out.c:DFS_write_tree_body.  */
       if (VAR_OR_FUNCTION_DECL_P (t)
 	  && DECL_EXTERNAL (t))
-	; /* stream_write_tree_shallow_non_ref (ob, t, ref_p); */
+	stream_write_tree_shallow_non_ref (ob, t, ref_p);
       else
 	stream_write_tree (ob, t, ref_p);