Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp	(revision 134172)
+++ lib/CodeGen/BackendUtil.cpp	(working copy)
@@ -278,6 +278,10 @@ bool EmitAssemblyHelper::AddEmitPasses(B
   if (CodeGenOpts.NoExecStack)
     TM->setMCNoExecStack(true);
 
+  assert(TM->getTargetData()->getStringRepresentation()
+           == TheModule->getDataLayout()
+         && "target machine's target data does not match module's");
+
   // Create the code generator passes.
   PassManager *PM = getCodeGenPasses();
   CodeGenOpt::Level OptLevel = CodeGenOpt::Default;