Index: lib/LTO/LTO.cpp
===================================================================
--- lib/LTO/LTO.cpp
+++ lib/LTO/LTO.cpp
@@ -320,8 +320,12 @@
   if (Conf.ResolutionFile)
     writeToResolutionFile(*Conf.ResolutionFile, Input.get(), Res);
 
-  // FIXME: move to backend
   Module &M = Input->Obj->getModule();
+  if (M.getDataLayoutStr().empty())
+    return make_error<StringError>("input module has no datalayout",
+                                    inconvertibleErrorCode());
+
+  // FIXME: move to backend
   if (!Conf.OverrideTriple.empty())
     M.setTargetTriple(Conf.OverrideTriple);
   else if (M.getTargetTriple().empty())
Index: test/tools/llvm-lto2/X86/nodatalayout.ll
===================================================================
--- /dev/null
+++ test/tools/llvm-lto2/X86/nodatalayout.ll
@@ -0,0 +1,13 @@
+; RUN: llvm-as < %s > %t1.bc
+
+; Reject input modules without a datalayout.
+; RUN: not llvm-lto2 %t1.bc -o %t.o \
+; RUN:  -r %t1.bc,patatino,px 2>&1 | FileCheck %s
+
+; CHECK: input module has no datalayout
+
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @patatino() {
+  ret void
+}