Index: include/llvm/Target/TargetMachine.h
===================================================================
--- include/llvm/Target/TargetMachine.h
+++ include/llvm/Target/TargetMachine.h
@@ -133,6 +133,16 @@
   /// Create a DataLayout.
   const DataLayout createDataLayout() const { return DL; }
 
+  /// Test if a DataLayout if compatible with the CodeGen for this target.
+  ///
+  /// The LLVM Module owns a DataLayout that is used for the target independent
+  /// optimizations and will be used for the CodeGen. This hook provide a target
+  /// specific check on the validity of this DataLayout. The default
+  /// implementation just check for an exact match but Targets can override it.
+  virtual bool isCompatibleDataLayout(const DataLayout &Candidate) const {
+    return DL == Candidate;
+  }
+
   /// Get the pointer size for this target.
   ///
   /// This is the only time the DataLayout in the TargetMachine is used.
Index: lib/CodeGen/MachineFunction.cpp
===================================================================
--- lib/CodeGen/MachineFunction.cpp
+++ lib/CodeGen/MachineFunction.cpp
@@ -85,6 +85,10 @@
 
   FunctionNumber = FunctionNum;
   JumpTableInfo = nullptr;
+
+  assert(TM.isCompatibleDataLayout(getDataLayout()) &&
+         "Can't create a MachineFunction using a Module with a "
+         "Target-incompatible DataLayout attached\n");
 }
 
 MachineFunction::~MachineFunction() {