diff --git a/include/llvm/CodeGen/MachineInstr.h b/include/llvm/CodeGen/MachineInstr.h
index 3c7b213533f..76738e28c26 100644
--- a/include/llvm/CodeGen/MachineInstr.h
+++ b/include/llvm/CodeGen/MachineInstr.h
@@ -43,6 +43,10 @@ class MachineMemOperand;
 //===----------------------------------------------------------------------===//
 /// MachineInstr - Representation of each machine instruction.
 ///
+/// This class isn't a POD type, but it must have a trivial destructor. When a
+/// MachineFunction is deleted, all the contained MachineInstrs are deallocated
+/// without having their destructor called.
+///
 class MachineInstr : public ilist_node<MachineInstr> {
 public:
   typedef MachineMemOperand **mmo_iterator;
@@ -90,6 +94,8 @@ private:
 
   MachineInstr(const MachineInstr&) LLVM_DELETED_FUNCTION;
   void operator=(const MachineInstr&) LLVM_DELETED_FUNCTION;
+  // Use MachineFunction::DeleteMachineInstr() instead.
+  ~MachineInstr() LLVM_DELETED_FUNCTION;
 
   // Intrusive list support
   friend struct ilist_traits<MachineInstr>;
@@ -106,8 +112,6 @@ private:
   MachineInstr(MachineFunction&, const MCInstrDesc &MCID,
                const DebugLoc dl, bool NoImp = false);
 
-  ~MachineInstr();
-
   // MachineInstrs are pool-allocated and owned by MachineFunction.
   friend class MachineFunction;
 
diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index 08d116afead..9647e83e24c 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -76,7 +76,13 @@ MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
 }
 
 MachineFunction::~MachineFunction() {
-  BasicBlocks.clear();
+  // Don't call destructors on MachineInstr and MachineOperand. All of their
+  // memory comes from the BumpPtrAllocator which is about to be purged.
+  //
+  // Do call MachineBasicBlock destructors, it contains std::vectors.
+  for (iterator I = begin(), E = end(); I != E; I = BasicBlocks.erase(I))
+    I->Insts.clearAndLeakNodesUnsafely();
+
   InstructionRecycler.clear(Allocator);
   OperandRecycler.clear(Allocator);
   BasicBlockRecycler.clear(Allocator);
@@ -176,15 +182,17 @@ MachineFunction::CloneMachineInstr(const MachineInstr *Orig) {
 
 /// DeleteMachineInstr - Delete the given MachineInstr.
 ///
+/// This function also serves as the MachineInstr destructor - the real
+/// ~MachineInstr() destructor must be empty.
 void
 MachineFunction::DeleteMachineInstr(MachineInstr *MI) {
   // Strip it for parts. The operand array and the MI object itself are
   // independently recyclable.
   if (MI->Operands)
     deallocateOperandArray(MI->CapOperands, MI->Operands);
-  MI->Operands = 0;
-  MI->NumOperands = 0;
-  MI->~MachineInstr();
+  // Don't call ~MachineInstr() which must be trivial anyway because
+  // ~MachineFunction drops whole lists of MachineInstrs wihout calling their
+  // destructors.
   InstructionRecycler.Deallocate(Allocator, MI);
 }
 
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index d3342987c05..3255fa6e451 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -35,7 +35,6 @@
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/LeakDetector.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetInstrInfo.h"
@@ -544,8 +543,6 @@ MachineInstr::MachineInstr(MachineFunction &MF, const MCInstrDesc &tid,
 
   if (!NoImp)
     addImplicitDefUseOperands(MF);
-  // Make sure that we get added to a machine basicblock
-  LeakDetector::addGarbageObject(this);
 }
 
 /// MachineInstr ctor - Copies MachineInstr arg exactly
@@ -558,28 +555,12 @@ MachineInstr::MachineInstr(MachineFunction &MF, const MachineInstr &MI)
   CapOperands = OperandCapacity::get(MI.getNumOperands());
   Operands = MF.allocateOperandArray(CapOperands);
 
-  // Add operands
+  // Copy operands.
   for (unsigned i = 0; i != MI.getNumOperands(); ++i)
     addOperand(MF, MI.getOperand(i));
 
   // Copy all the sensible flags.
   setFlags(MI.Flags);
-
-  // Set parent to null.
-  Parent = 0;
-
-  LeakDetector::addGarbageObject(this);
-}
-
-MachineInstr::~MachineInstr() {
-  LeakDetector::removeGarbageObject(this);
-#ifndef NDEBUG
-  for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
-    assert(Operands[i].ParentMI == this && "ParentMI mismatch!");
-    assert((!Operands[i].isReg() || !Operands[i].isOnRegUseList()) &&
-           "Reg operand def/use list corrupted");
-  }
-#endif
 }
 
 /// getRegInfo - If this instruction is embedded into a MachineFunction,
diff --git a/lib/CodeGen/MachineRegisterInfo.cpp b/lib/CodeGen/MachineRegisterInfo.cpp
index 9858b4999e0..21877e52c25 100644
--- a/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/lib/CodeGen/MachineRegisterInfo.cpp
@@ -30,12 +30,6 @@ MachineRegisterInfo::MachineRegisterInfo(const TargetRegisterInfo &TRI)
 }
 
 MachineRegisterInfo::~MachineRegisterInfo() {
-#ifndef NDEBUG
-  clearVirtRegs();
-  for (unsigned i = 0, e = TRI->getNumRegs(); i != e; ++i)
-    assert(!PhysRegUseDefLists[i] &&
-           "PhysRegUseDefLists has entries after all instructions are deleted");
-#endif
   delete [] PhysRegUseDefLists;
 }