diff --git a/src/mips/code-stubs-mips.cc b/src/mips/code-stubs-mips.cc
index 5d0dbc467d..2eefc82196 100644
--- a/src/mips/code-stubs-mips.cc
+++ b/src/mips/code-stubs-mips.cc
@@ -227,8 +227,20 @@ void InternalArrayNArgumentsConstructorStub::InitializeInterfaceDescriptor(
 }
 
 
+void UnaryOpStub::InitializeInterfaceDescriptor(
+    Isolate* isolate,
+    CodeStubInterfaceDescriptor* descriptor) {
+  static Register registers[] = { a0 };
+  descriptor->register_param_count_ = 1;
+  descriptor->register_params_ = registers;
+  descriptor->deoptimization_handler_ =
+      FUNCTION_ADDR(UnaryOpIC_Miss);
+}
+
+
 #define __ ACCESS_MASM(masm)
 
+
 static void EmitIdenticalObjectComparison(MacroAssembler* masm,
                                           Label* slow,
                                           Condition cc);
@@ -1586,294 +1598,6 @@ void StoreBufferOverflowStub::Generate(MacroAssembler* masm) {
 }
 
 
-void UnaryOpStub::PrintName(StringStream* stream) {
-  const char* op_name = Token::Name(op_);
-  const char* overwrite_name = NULL;  // Make g++ happy.
-  switch (mode_) {
-    case UNARY_NO_OVERWRITE: overwrite_name = "Alloc"; break;
-    case UNARY_OVERWRITE: overwrite_name = "Overwrite"; break;
-  }
-  stream->Add("UnaryOpStub_%s_%s_%s",
-              op_name,
-              overwrite_name,
-              UnaryOpIC::GetName(operand_type_));
-}
-
-
-// TODO(svenpanne): Use virtual functions instead of switch.
-void UnaryOpStub::Generate(MacroAssembler* masm) {
-  switch (operand_type_) {
-    case UnaryOpIC::UNINITIALIZED:
-      GenerateTypeTransition(masm);
-      break;
-    case UnaryOpIC::SMI:
-      GenerateSmiStub(masm);
-      break;
-    case UnaryOpIC::NUMBER:
-      GenerateNumberStub(masm);
-      break;
-    case UnaryOpIC::GENERIC:
-      GenerateGenericStub(masm);
-      break;
-  }
-}
-
-
-void UnaryOpStub::GenerateTypeTransition(MacroAssembler* masm) {
-  // Argument is in a0 and v0 at this point, so we can overwrite a0.
-  __ li(a2, Operand(Smi::FromInt(op_)));
-  __ li(a1, Operand(Smi::FromInt(mode_)));
-  __ li(a0, Operand(Smi::FromInt(operand_type_)));
-  __ Push(v0, a2, a1, a0);
-
-  __ TailCallExternalReference(
-      ExternalReference(IC_Utility(IC::kUnaryOp_Patch), masm->isolate()), 4, 1);
-}
-
-
-// TODO(svenpanne): Use virtual functions instead of switch.
-void UnaryOpStub::GenerateSmiStub(MacroAssembler* masm) {
-  switch (op_) {
-    case Token::SUB:
-      GenerateSmiStubSub(masm);
-      break;
-    case Token::BIT_NOT:
-      GenerateSmiStubBitNot(masm);
-      break;
-    default:
-      UNREACHABLE();
-  }
-}
-
-
-void UnaryOpStub::GenerateSmiStubSub(MacroAssembler* masm) {
-  Label non_smi, slow;
-  GenerateSmiCodeSub(masm, &non_smi, &slow);
-  __ bind(&non_smi);
-  __ bind(&slow);
-  GenerateTypeTransition(masm);
-}
-
-
-void UnaryOpStub::GenerateSmiStubBitNot(MacroAssembler* masm) {
-  Label non_smi;
-  GenerateSmiCodeBitNot(masm, &non_smi);
-  __ bind(&non_smi);
-  GenerateTypeTransition(masm);
-}
-
-
-void UnaryOpStub::GenerateSmiCodeSub(MacroAssembler* masm,
-                                     Label* non_smi,
-                                     Label* slow) {
-  __ JumpIfNotSmi(a0, non_smi);
-
-  // The result of negating zero or the smallest negative smi is not a smi.
-  __ And(t0, a0, ~0x80000000);
-  __ Branch(slow, eq, t0, Operand(zero_reg));
-
-  // Return '0 - value'.
-  __ Ret(USE_DELAY_SLOT);
-  __ subu(v0, zero_reg, a0);
-}
-
-
-void UnaryOpStub::GenerateSmiCodeBitNot(MacroAssembler* masm,
-                                        Label* non_smi) {
-  __ JumpIfNotSmi(a0, non_smi);
-
-  // Flip bits and revert inverted smi-tag.
-  __ Neg(v0, a0);
-  __ And(v0, v0, ~kSmiTagMask);
-  __ Ret();
-}
-
-
-// TODO(svenpanne): Use virtual functions instead of switch.
-void UnaryOpStub::GenerateNumberStub(MacroAssembler* masm) {
-  switch (op_) {
-    case Token::SUB:
-      GenerateNumberStubSub(masm);
-      break;
-    case Token::BIT_NOT:
-      GenerateNumberStubBitNot(masm);
-      break;
-    default:
-      UNREACHABLE();
-  }
-}
-
-
-void UnaryOpStub::GenerateNumberStubSub(MacroAssembler* masm) {
-  Label non_smi, slow, call_builtin;
-  GenerateSmiCodeSub(masm, &non_smi, &call_builtin);
-  __ bind(&non_smi);
-  GenerateHeapNumberCodeSub(masm, &slow);
-  __ bind(&slow);
-  GenerateTypeTransition(masm);
-  __ bind(&call_builtin);
-  GenerateGenericCodeFallback(masm);
-}
-
-
-void UnaryOpStub::GenerateNumberStubBitNot(MacroAssembler* masm) {
-  Label non_smi, slow;
-  GenerateSmiCodeBitNot(masm, &non_smi);
-  __ bind(&non_smi);
-  GenerateHeapNumberCodeBitNot(masm, &slow);
-  __ bind(&slow);
-  GenerateTypeTransition(masm);
-}
-
-
-void UnaryOpStub::GenerateHeapNumberCodeSub(MacroAssembler* masm,
-                                            Label* slow) {
-  EmitCheckForHeapNumber(masm, a0, a1, t2, slow);
-  // a0 is a heap number.  Get a new heap number in a1.
-  if (mode_ == UNARY_OVERWRITE) {
-    __ lw(a2, FieldMemOperand(a0, HeapNumber::kExponentOffset));
-    __ Xor(a2, a2, Operand(HeapNumber::kSignMask));  // Flip sign.
-    __ Ret(USE_DELAY_SLOT);
-    __ sw(a2, FieldMemOperand(a0, HeapNumber::kExponentOffset));
-  } else {
-    Label slow_allocate_heapnumber, heapnumber_allocated;
-    __ AllocateHeapNumber(a1, a2, a3, t2, &slow_allocate_heapnumber);
-    __ jmp(&heapnumber_allocated);
-
-    __ bind(&slow_allocate_heapnumber);
-    {
-      FrameScope scope(masm, StackFrame::INTERNAL);
-      __ push(a0);
-      __ CallRuntime(Runtime::kNumberAlloc, 0);
-      __ mov(a1, v0);
-      __ pop(a0);
-    }
-
-    __ bind(&heapnumber_allocated);
-    __ lw(a3, FieldMemOperand(a0, HeapNumber::kMantissaOffset));
-    __ lw(a2, FieldMemOperand(a0, HeapNumber::kExponentOffset));
-    __ sw(a3, FieldMemOperand(a1, HeapNumber::kMantissaOffset));
-    __ Xor(a2, a2, Operand(HeapNumber::kSignMask));  // Flip sign.
-    __ sw(a2, FieldMemOperand(a1, HeapNumber::kExponentOffset));
-    __ Ret(USE_DELAY_SLOT);
-    __ mov(v0, a1);
-  }
-}
-
-
-void UnaryOpStub::GenerateHeapNumberCodeBitNot(
-    MacroAssembler* masm,
-    Label* slow) {
-  Label impossible;
-
-  EmitCheckForHeapNumber(masm, a0, a1, t2, slow);
-  // Convert the heap number in a0 to an untagged integer in a1.
-  __ ConvertToInt32(a0, a1, a2, a3, f0, slow);
-
-  // Do the bitwise operation and check if the result fits in a smi.
-  Label try_float;
-  __ Neg(a1, a1);
-  __ Addu(a2, a1, Operand(0x40000000));
-  __ Branch(&try_float, lt, a2, Operand(zero_reg));
-
-  // Tag the result as a smi and we're done.
-  __ Ret(USE_DELAY_SLOT);  // SmiTag emits one instruction in delay slot.
-  __ SmiTag(v0, a1);
-
-  // Try to store the result in a heap number.
-  __ bind(&try_float);
-  if (mode_ == UNARY_NO_OVERWRITE) {
-    Label slow_allocate_heapnumber, heapnumber_allocated;
-    // Allocate a new heap number without zapping v0, which we need if it fails.
-    __ AllocateHeapNumber(a2, a3, t0, t2, &slow_allocate_heapnumber);
-    __ jmp(&heapnumber_allocated);
-
-    __ bind(&slow_allocate_heapnumber);
-    {
-      FrameScope scope(masm, StackFrame::INTERNAL);
-      __ push(v0);  // Push the heap number, not the untagged int32.
-      __ CallRuntime(Runtime::kNumberAlloc, 0);
-      __ mov(a2, v0);  // Move the new heap number into a2.
-      // Get the heap number into v0, now that the new heap number is in a2.
-      __ pop(v0);
-    }
-
-    // Convert the heap number in v0 to an untagged integer in a1.
-    // This can't go slow-case because it's the same number we already
-    // converted once again.
-    __ ConvertToInt32(v0, a1, a3, t0, f0, &impossible);
-    // Negate the result.
-    __ Xor(a1, a1, -1);
-
-    __ bind(&heapnumber_allocated);
-    __ mov(v0, a2);  // Move newly allocated heap number to v0.
-  }
-
-  // Convert the int32 in a1 to the heap number in v0. a2 is corrupted.
-  __ mtc1(a1, f0);
-  __ cvt_d_w(f0, f0);
-  __ sdc1(f0, FieldMemOperand(v0, HeapNumber::kValueOffset));
-  __ Ret();
-
-  __ bind(&impossible);
-  if (FLAG_debug_code) {
-    __ stop("Incorrect assumption in bit-not stub");
-  }
-}
-
-
-// TODO(svenpanne): Use virtual functions instead of switch.
-void UnaryOpStub::GenerateGenericStub(MacroAssembler* masm) {
-  switch (op_) {
-    case Token::SUB:
-      GenerateGenericStubSub(masm);
-      break;
-    case Token::BIT_NOT:
-      GenerateGenericStubBitNot(masm);
-      break;
-    default:
-      UNREACHABLE();
-  }
-}
-
-
-void UnaryOpStub::GenerateGenericStubSub(MacroAssembler* masm) {
-  Label non_smi, slow;
-  GenerateSmiCodeSub(masm, &non_smi, &slow);
-  __ bind(&non_smi);
-  GenerateHeapNumberCodeSub(masm, &slow);
-  __ bind(&slow);
-  GenerateGenericCodeFallback(masm);
-}
-
-
-void UnaryOpStub::GenerateGenericStubBitNot(MacroAssembler* masm) {
-  Label non_smi, slow;
-  GenerateSmiCodeBitNot(masm, &non_smi);
-  __ bind(&non_smi);
-  GenerateHeapNumberCodeBitNot(masm, &slow);
-  __ bind(&slow);
-  GenerateGenericCodeFallback(masm);
-}
-
-
-void UnaryOpStub::GenerateGenericCodeFallback(
-    MacroAssembler* masm) {
-  // Handle the slow case by jumping to the JavaScript builtin.
-  __ push(a0);
-  switch (op_) {
-    case Token::SUB:
-      __ InvokeBuiltin(Builtins::UNARY_MINUS, JUMP_FUNCTION);
-      break;
-    case Token::BIT_NOT:
-      __ InvokeBuiltin(Builtins::BIT_NOT, JUMP_FUNCTION);
-      break;
-    default:
-      UNREACHABLE();
-  }
-}
-
-
 void BinaryOpStub::Initialize() {
   platform_specific_bit_ = true;  // FPU is a base requirement for V8.
 }
diff --git a/src/mips/code-stubs-mips.h b/src/mips/code-stubs-mips.h
index bf5db10f63..afef979f79 100644
--- a/src/mips/code-stubs-mips.h
+++ b/src/mips/code-stubs-mips.h
@@ -81,71 +81,6 @@ class StoreBufferOverflowStub: public PlatformCodeStub {
 };
 
 
-class UnaryOpStub: public PlatformCodeStub {
- public:
-  UnaryOpStub(Token::Value op,
-              UnaryOverwriteMode mode,
-              UnaryOpIC::TypeInfo operand_type = UnaryOpIC::UNINITIALIZED)
-      : op_(op),
-        mode_(mode),
-        operand_type_(operand_type) {
-  }
-
- private:
-  Token::Value op_;
-  UnaryOverwriteMode mode_;
-
-  // Operand type information determined at runtime.
-  UnaryOpIC::TypeInfo operand_type_;
-
-  virtual void PrintName(StringStream* stream);
-
-  class ModeBits: public BitField<UnaryOverwriteMode, 0, 1> {};
-  class OpBits: public BitField<Token::Value, 1, 7> {};
-  class OperandTypeInfoBits: public BitField<UnaryOpIC::TypeInfo, 8, 3> {};
-
-  Major MajorKey() { return UnaryOp; }
-  int MinorKey() {
-    return ModeBits::encode(mode_)
-           | OpBits::encode(op_)
-           | OperandTypeInfoBits::encode(operand_type_);
-  }
-
-  // Note: A lot of the helper functions below will vanish when we use virtual
-  // function instead of switch more often.
-  void Generate(MacroAssembler* masm);
-
-  void GenerateTypeTransition(MacroAssembler* masm);
-
-  void GenerateSmiStub(MacroAssembler* masm);
-  void GenerateSmiStubSub(MacroAssembler* masm);
-  void GenerateSmiStubBitNot(MacroAssembler* masm);
-  void GenerateSmiCodeSub(MacroAssembler* masm, Label* non_smi, Label* slow);
-  void GenerateSmiCodeBitNot(MacroAssembler* masm, Label* slow);
-
-  void GenerateNumberStub(MacroAssembler* masm);
-  void GenerateNumberStubSub(MacroAssembler* masm);
-  void GenerateNumberStubBitNot(MacroAssembler* masm);
-  void GenerateHeapNumberCodeSub(MacroAssembler* masm, Label* slow);
-  void GenerateHeapNumberCodeBitNot(MacroAssembler* masm, Label* slow);
-
-  void GenerateGenericStub(MacroAssembler* masm);
-  void GenerateGenericStubSub(MacroAssembler* masm);
-  void GenerateGenericStubBitNot(MacroAssembler* masm);
-  void GenerateGenericCodeFallback(MacroAssembler* masm);
-
-  virtual Code::Kind GetCodeKind() const { return Code::UNARY_OP_IC; }
-
-  virtual InlineCacheState GetICState() {
-    return UnaryOpIC::ToState(operand_type_);
-  }
-
-  virtual void FinishCode(Handle<Code> code) {
-    code->set_unary_op_type(operand_type_);
-  }
-};
-
-
 class StringHelper : public AllStatic {
  public:
   // Generate code for copying characters using a simple loop. This should only
diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index 032c1f5e5b..43325dfb2c 100644
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -4400,10 +4400,7 @@ void FullCodeGenerator::EmitUnaryOperation(UnaryOperation* expr,
                                            const char* comment) {
   // TODO(svenpanne): Allowing format strings in Comment would be nice here...
   Comment cmt(masm_, comment);
-  bool can_overwrite = expr->expression()->ResultOverwriteAllowed();
-  UnaryOverwriteMode overwrite =
-      can_overwrite ? UNARY_OVERWRITE : UNARY_NO_OVERWRITE;
-  UnaryOpStub stub(expr->op(), overwrite);
+  UnaryOpStub stub(expr->op());
   // GenericUnaryOpStub expects the argument to be in a0.
   VisitForAccumulatorValue(expr->expression());
   SetSourcePosition(expr->position());
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index a2f94fa5d4..ade50ac6e0 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -1971,11 +1971,11 @@ int LCodeGen::GetNextEmittedBlock() const {
 template<class InstrType>
 void LCodeGen::EmitBranch(InstrType instr,
                           Condition cc, Register src1, const Operand& src2) {
-  int right_block = instr->FalseDestination(chunk_);
   int left_block = instr->TrueDestination(chunk_);
+  int right_block = instr->FalseDestination(chunk_);
 
   int next_block = GetNextEmittedBlock();
-  if (right_block == left_block) {
+  if (right_block == left_block || cc == al) {
     EmitGoto(left_block);
   } else if (left_block == next_block) {
     __ Branch(chunk_->GetAssemblyLabel(right_block),
@@ -2015,6 +2015,25 @@ void LCodeGen::DoDebugBreak(LDebugBreak* instr) {
 }
 
 
+void LCodeGen::DoIsNumberAndBranch(LIsNumberAndBranch* instr) {
+  Representation r = instr->hydrogen()->value()->representation();
+  if (r.IsSmiOrInteger32() || r.IsDouble()) {
+    EmitBranch(instr, al, zero_reg, Operand(zero_reg));
+  } else {
+    ASSERT(r.IsTagged());
+    Register reg = ToRegister(instr->value());
+    HType type = instr->hydrogen()->value()->type();
+    if (type.IsTaggedNumber()) {
+      EmitBranch(instr, al, zero_reg, Operand(zero_reg));
+    }
+    __ JumpIfSmi(reg, instr->TrueLabel(chunk_));
+    __ lw(scratch0(), FieldMemOperand(reg, HeapObject::kMapOffset));
+    __ LoadRoot(at, Heap::kHeapNumberMapRootIndex);
+    EmitBranch(instr, eq, scratch0(), Operand(at));
+  }
+}
+
+
 void LCodeGen::DoBranch(LBranch* instr) {
   Representation r = instr->hydrogen()->value()->representation();
   if (r.IsInteger32() || r.IsSmi()) {
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index d76200f28f..8c64ebe6e7 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1919,6 +1919,18 @@ LInstruction* LChunkBuilder::DoCheckHeapObject(HCheckHeapObject* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoCheckSmi(HCheckSmi* instr) {
+  LOperand* value = UseRegisterAtStart(instr->value());
+  return AssignEnvironment(new(zone()) LCheckSmi(value));
+}
+
+
+LInstruction* LChunkBuilder::DoIsNumberAndBranch(HIsNumberAndBranch* instr) {
+  return new(zone())
+    LIsNumberAndBranch(UseRegisterOrConstantAtStart(instr->value()));
+}
+
+
 LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
   LInstruction* result = new(zone()) LCheckInstanceType(value);
diff --git a/src/mips/lithium-mips.h b/src/mips/lithium-mips.h
index 06d30d03de..7ae2dd380b 100644
--- a/src/mips/lithium-mips.h
+++ b/src/mips/lithium-mips.h
@@ -118,6 +118,7 @@ class LCodeGen;
   V(IsConstructCallAndBranch)                   \
   V(IsObjectAndBranch)                          \
   V(IsStringAndBranch)                          \
+  V(IsNumberAndBranch)                          \
   V(IsSmiAndBranch)                             \
   V(IsUndetectableAndBranch)                    \
   V(Label)                                      \
@@ -919,6 +920,19 @@ class LIsObjectAndBranch: public LControlInstruction<1, 1> {
 };
 
 
+class LIsNumberAndBranch: public LControlInstruction<1, 0> {
+ public:
+  explicit LIsNumberAndBranch(LOperand* value) {
+    inputs_[0] = value;
+  }
+
+  LOperand* value() { return inputs_[0]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(IsNumberAndBranch, "is-number-and-branch")
+  DECLARE_HYDROGEN_ACCESSOR(IsNumberAndBranch)
+};
+
+
 class LIsStringAndBranch: public LControlInstruction<1, 1> {
  public:
   LIsStringAndBranch(LOperand* value, LOperand* temp) {