Index: llvm/include/llvm/ADT/ilist.h
===================================================================
--- llvm/include/llvm/ADT/ilist.h
+++ llvm/include/llvm/ADT/ilist.h
@@ -65,9 +65,8 @@
   void addNodeToList(NodeTy *) {}
   void removeNodeFromList(NodeTy *) {}
 
-  /// Callback before transferring nodes to this list.
-  ///
-  /// \pre \c this!=&OldList
+  /// Callback before transferring nodes to this list. The nodes may already be
+  /// in this same list.
   template <class Iterator>
   void transferNodesFromList(ilist_callback_traits &OldList, Iterator /*first*/,
                              Iterator /*last*/) {
@@ -286,8 +285,8 @@
     if (position == last)
       return;
 
-    if (this != &L2) // Notify traits we moved the nodes...
-      this->transferNodesFromList(L2, first, last);
+    // Notify traits we moved the nodes...
+    this->transferNodesFromList(L2, first, last);
 
     base_list_type::splice(position, L2, first, last);
   }
Index: llvm/include/llvm/CodeGen/MachineFunction.h
===================================================================
--- llvm/include/llvm/CodeGen/MachineFunction.h
+++ llvm/include/llvm/CodeGen/MachineFunction.h
@@ -85,7 +85,7 @@
 
   template <class Iterator>
   void transferNodesFromList(ilist_callback_traits &OldList, Iterator, Iterator) {
-    llvm_unreachable("Never transfer between lists");
+    assert(this == &OldList && "never transfer MBBs between functions");
   }
 };
 
Index: llvm/lib/CodeGen/MachineBasicBlock.cpp
===================================================================
--- llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -132,8 +132,12 @@
                                                        instr_iterator First,
                                                        instr_iterator Last) {
   assert(Parent->getParent() == FromList.Parent->getParent() &&
-        "MachineInstr parent mismatch!");
-  assert(this != &FromList && "Called without a real transfer...");
+         "cannot transfer MachineInstrs between MachineFunctions");
+
+  // If it's within the same BB, there's nothing to do.
+  if (this == &FromList)
+    return;
+
   assert(Parent != FromList.Parent && "Two lists have the same parent?");
 
   // If splicing between two blocks within the same function, just update the
Index: llvm/lib/IR/SymbolTableListTraitsImpl.h
===================================================================
--- llvm/lib/IR/SymbolTableListTraitsImpl.h
+++ llvm/lib/IR/SymbolTableListTraitsImpl.h
@@ -83,7 +83,8 @@
     SymbolTableListTraits &L2, iterator first, iterator last) {
   // We only have to do work here if transferring instructions between BBs
   ItemParentClass *NewIP = getListOwner(), *OldIP = L2.getListOwner();
-  assert(NewIP != OldIP && "Expected different list owners");
+  if (NewIP == OldIP)
+    return;
 
   // We only have to update symbol table entries if we are transferring the
   // instructions to a different symtab object...