Index: llvm/trunk/lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- llvm/trunk/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ llvm/trunk/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -3271,9 +3271,6 @@
 /// Emit the per-module summary section alongside the rest of
 /// the module's bitcode.
 void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
-  if (M.empty())
-    return;
-
   if (Index->begin() == Index->end())
     return;
 
Index: llvm/trunk/test/Bitcode/thinlto-summary-globalvar.ll
===================================================================
--- llvm/trunk/test/Bitcode/thinlto-summary-globalvar.ll
+++ llvm/trunk/test/Bitcode/thinlto-summary-globalvar.ll
@@ -0,0 +1,5 @@
+; RUN: opt -module-summary %s -o - | llvm-bcanalyzer -dump | FileCheck %s
+
+; CHECK: <GLOBALVAL_SUMMARY_BLOCK
+
+@a = global i32 0