diff --git a/test/unittests/compiler/typer-unittest.cc b/test/unittests/compiler/typer-unittest.cc
new file mode 100644
index 0000000..6e4d4d5
--- /dev/null
+++ b/test/unittests/compiler/typer-unittest.cc
@@ -0,0 +1,435 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <functional>
+
+#include "src/codegen.h"
+#include "src/compiler/js-operator.h"
+#include "src/compiler/node-properties.h"
+#include "src/compiler/operator-properties.h"
+#include "test/cctest/types-fuzz.h"
+#include "test/unittests/compiler/graph-unittest.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+// TODO(titzer): generate a large set of deterministic inputs for these tests.
+class TyperTest : public TypedGraphTest {
+ public:
+  TyperTest()
+      : TypedGraphTest(3),
+        types_(zone(), isolate(), random_number_generator()),
+        javascript_(zone()) {
+    context_node_ = graph()->NewNode(common()->Parameter(2), graph()->start());
+    rng_ = random_number_generator();
+
+    integers.push_back(0);
+    integers.push_back(0);
+    integers.push_back(-1);
+    integers.push_back(+1);
+    integers.push_back(-V8_INFINITY);
+    integers.push_back(+V8_INFINITY);
+    for (int i = 0; i < 5; ++i) {
+      double x = rng_->NextInt();
+      integers.push_back(x);
+      x *= rng_->NextInt();
+      if (!IsMinusZero(x)) integers.push_back(x);
+    }
+
+    int32s.push_back(0);
+    int32s.push_back(0);
+    int32s.push_back(-1);
+    int32s.push_back(+1);
+    int32s.push_back(kMinInt);
+    int32s.push_back(kMaxInt);
+    for (int i = 0; i < 10; ++i) {
+      int32s.push_back(rng_->NextInt());
+    }
+  }
+
+  Types<Type, Type*, Zone> types_;
+  JSOperatorBuilder javascript_;
+  BinaryOperationHints const hints_ = BinaryOperationHints::Any();
+  Node* context_node_;
+  v8::base::RandomNumberGenerator* rng_;
+  std::vector<double> integers;
+  std::vector<double> int32s;
+
+  Type* TypeBinaryOp(const Operator* op, Type* lhs, Type* rhs) {
+    Node* p0 = Parameter(0);
+    Node* p1 = Parameter(1);
+    NodeProperties::SetType(p0, lhs);
+    NodeProperties::SetType(p1, rhs);
+    std::vector<Node*> inputs;
+    inputs.push_back(p0);
+    inputs.push_back(p1);
+    if (OperatorProperties::HasContextInput(op)) {
+      inputs.push_back(context_node_);
+    }
+    for (int i = 0; i < OperatorProperties::GetFrameStateInputCount(op); i++) {
+      inputs.push_back(EmptyFrameState());
+    }
+    for (int i = 0; i < op->EffectInputCount(); i++) {
+      inputs.push_back(graph()->start());
+    }
+    for (int i = 0; i < op->ControlInputCount(); i++) {
+      inputs.push_back(graph()->start());
+    }
+    Node* n = graph()->NewNode(op, static_cast<int>(inputs.size()),
+                               &(inputs.front()));
+    return NodeProperties::GetType(n);
+  }
+
+  Type* RandomRange(bool int32 = false) {
+    std::vector<double>& numbers = int32 ? int32s : integers;
+    double i = numbers[rng_->NextInt(static_cast<int>(numbers.size()))];
+    double j = numbers[rng_->NextInt(static_cast<int>(numbers.size()))];
+    return NewRange(i, j);
+  }
+
+  Type* NewRange(double i, double j) {
+    if (i > j) std::swap(i, j);
+    return Type::Range(i, j, zone());
+  }
+
+  double RandomInt(double min, double max) {
+    switch (rng_->NextInt(4)) {
+      case 0:
+        return min;
+      case 1:
+        return max;
+      default:
+        break;
+    }
+    if (min == +V8_INFINITY) return +V8_INFINITY;
+    if (max == -V8_INFINITY) return -V8_INFINITY;
+    if (min == -V8_INFINITY && max == +V8_INFINITY) {
+      return rng_->NextInt() * static_cast<double>(rng_->NextInt());
+    }
+    double result = nearbyint(min + (max - min) * rng_->NextDouble());
+    if (IsMinusZero(result)) return 0;
+    if (std::isnan(result)) return rng_->NextInt(2) ? min : max;
+    DCHECK(min <= result && result <= max);
+    return result;
+  }
+
+  double RandomInt(Type::RangeType* range) {
+    return RandomInt(range->Min(), range->Max());
+  }
+
+  // Careful, this function runs O(max_width^5) trials.
+  template <class BinaryFunction>
+  void TestBinaryArithOpCloseToZero(const Operator* op, BinaryFunction opfun,
+                                    int max_width) {
+    const int min_min = -2 - max_width / 2;
+    const int max_min = 2 + max_width / 2;
+    for (int width = 0; width < max_width; width++) {
+      for (int lmin = min_min; lmin <= max_min; lmin++) {
+        for (int rmin = min_min; rmin <= max_min; rmin++) {
+          Type* r1 = NewRange(lmin, lmin + width);
+          Type* r2 = NewRange(rmin, rmin + width);
+          Type* expected_type = TypeBinaryOp(op, r1, r2);
+
+          for (int x1 = lmin; x1 < lmin + width; x1++) {
+            for (int x2 = rmin; x2 < rmin + width; x2++) {
+              double result_value = opfun(x1, x2);
+              Type* result_type = Type::Constant(
+                  isolate()->factory()->NewNumber(result_value), zone());
+              EXPECT_TRUE(result_type->Is(expected_type));
+            }
+          }
+        }
+      }
+    }
+  }
+
+  template <class BinaryFunction>
+  void TestBinaryArithOp(const Operator* op, BinaryFunction opfun) {
+    TestBinaryArithOpCloseToZero(op, opfun, 8);
+    for (int i = 0; i < 100; ++i) {
+      Type::RangeType* r1 = RandomRange()->AsRange();
+      Type::RangeType* r2 = RandomRange()->AsRange();
+      Type* expected_type = TypeBinaryOp(op, r1, r2);
+      for (int i = 0; i < 10; i++) {
+        double x1 = RandomInt(r1);
+        double x2 = RandomInt(r2);
+        double result_value = opfun(x1, x2);
+        Type* result_type = Type::Constant(
+            isolate()->factory()->NewNumber(result_value), zone());
+        EXPECT_TRUE(result_type->Is(expected_type));
+      }
+    }
+  }
+
+  template <class BinaryFunction>
+  void TestBinaryCompareOp(const Operator* op, BinaryFunction opfun) {
+    for (int i = 0; i < 100; ++i) {
+      Type::RangeType* r1 = RandomRange()->AsRange();
+      Type::RangeType* r2 = RandomRange()->AsRange();
+      Type* expected_type = TypeBinaryOp(op, r1, r2);
+      for (int i = 0; i < 10; i++) {
+        double x1 = RandomInt(r1);
+        double x2 = RandomInt(r2);
+        bool result_value = opfun(x1, x2);
+        Type* result_type =
+            Type::Constant(result_value ? isolate()->factory()->true_value()
+                                        : isolate()->factory()->false_value(),
+                           zone());
+        EXPECT_TRUE(result_type->Is(expected_type));
+      }
+    }
+  }
+
+  template <class BinaryFunction>
+  void TestBinaryBitOp(const Operator* op, BinaryFunction opfun) {
+    for (int i = 0; i < 100; ++i) {
+      Type::RangeType* r1 = RandomRange(true)->AsRange();
+      Type::RangeType* r2 = RandomRange(true)->AsRange();
+      Type* expected_type = TypeBinaryOp(op, r1, r2);
+      for (int i = 0; i < 10; i++) {
+        int32_t x1 = static_cast<int32_t>(RandomInt(r1));
+        int32_t x2 = static_cast<int32_t>(RandomInt(r2));
+        double result_value = opfun(x1, x2);
+        Type* result_type = Type::Constant(
+            isolate()->factory()->NewNumber(result_value), zone());
+        EXPECT_TRUE(result_type->Is(expected_type));
+      }
+    }
+  }
+
+  Type* RandomSubtype(Type* type) {
+    Type* subtype;
+    do {
+      subtype = types_.Fuzz();
+    } while (!subtype->Is(type));
+    return subtype;
+  }
+
+  void TestBinaryMonotonicity(const Operator* op) {
+    for (int i = 0; i < 50; ++i) {
+      Type* type1 = types_.Fuzz();
+      Type* type2 = types_.Fuzz();
+      Type* type = TypeBinaryOp(op, type1, type2);
+      Type* subtype1 = RandomSubtype(type1);
+      Type* subtype2 = RandomSubtype(type2);
+      Type* subtype = TypeBinaryOp(op, subtype1, subtype2);
+      EXPECT_TRUE(subtype->Is(type));
+    }
+  }
+};
+
+
+namespace {
+
+int32_t shift_left(int32_t x, int32_t y) { return x << y; }
+int32_t shift_right(int32_t x, int32_t y) { return x >> y; }
+int32_t bit_or(int32_t x, int32_t y) { return x | y; }
+int32_t bit_and(int32_t x, int32_t y) { return x & y; }
+int32_t bit_xor(int32_t x, int32_t y) { return x ^ y; }
+
+}  // namespace
+
+
+//------------------------------------------------------------------------------
+// Soundness
+//   For simplicity, we currently only test soundness on expression operators
+//   that have a direct equivalent in C++.  Also, testing is currently limited
+//   to ranges as input types.
+
+
+TEST_F(TyperTest, TypeJSAdd) {
+  TestBinaryArithOp(javascript_.Add(LanguageMode::SLOPPY, hints_),
+                    std::plus<double>());
+  TestBinaryArithOp(javascript_.Add(LanguageMode::STRONG, hints_),
+                    std::plus<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSSubtract) {
+  TestBinaryArithOp(javascript_.Subtract(LanguageMode::SLOPPY, hints_),
+                    std::minus<double>());
+  TestBinaryArithOp(javascript_.Subtract(LanguageMode::STRONG, hints_),
+                    std::minus<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSMultiply) {
+  TestBinaryArithOp(javascript_.Multiply(LanguageMode::SLOPPY, hints_),
+                    std::multiplies<double>());
+  TestBinaryArithOp(javascript_.Multiply(LanguageMode::STRONG, hints_),
+                    std::multiplies<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSDivide) {
+  TestBinaryArithOp(javascript_.Divide(LanguageMode::SLOPPY, hints_),
+                    std::divides<double>());
+  TestBinaryArithOp(javascript_.Divide(LanguageMode::STRONG, hints_),
+                    std::divides<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSModulus) {
+  TestBinaryArithOp(javascript_.Modulus(LanguageMode::SLOPPY, hints_), modulo);
+  TestBinaryArithOp(javascript_.Modulus(LanguageMode::STRONG, hints_), modulo);
+}
+
+
+TEST_F(TyperTest, TypeJSBitwiseOr) {
+  TestBinaryBitOp(javascript_.BitwiseOr(LanguageMode::SLOPPY, hints_), bit_or);
+  TestBinaryBitOp(javascript_.BitwiseOr(LanguageMode::STRONG, hints_), bit_or);
+}
+
+
+TEST_F(TyperTest, TypeJSBitwiseAnd) {
+  TestBinaryBitOp(javascript_.BitwiseAnd(LanguageMode::SLOPPY, hints_),
+                  bit_and);
+  TestBinaryBitOp(javascript_.BitwiseAnd(LanguageMode::STRONG, hints_),
+                  bit_and);
+}
+
+
+TEST_F(TyperTest, TypeJSBitwiseXor) {
+  TestBinaryBitOp(javascript_.BitwiseXor(LanguageMode::SLOPPY, hints_),
+                  bit_xor);
+  TestBinaryBitOp(javascript_.BitwiseXor(LanguageMode::STRONG, hints_),
+                  bit_xor);
+}
+
+
+TEST_F(TyperTest, TypeJSShiftLeft) {
+  TestBinaryBitOp(javascript_.ShiftLeft(LanguageMode::SLOPPY, hints_),
+                  shift_left);
+  TestBinaryBitOp(javascript_.ShiftLeft(LanguageMode::STRONG, hints_),
+                  shift_left);
+}
+
+
+TEST_F(TyperTest, TypeJSShiftRight) {
+  TestBinaryBitOp(javascript_.ShiftRight(LanguageMode::SLOPPY, hints_),
+                  shift_right);
+  TestBinaryBitOp(javascript_.ShiftRight(LanguageMode::STRONG, hints_),
+                  shift_right);
+}
+
+
+TEST_F(TyperTest, TypeJSLessThan) {
+  TestBinaryCompareOp(javascript_.LessThan(LanguageMode::SLOPPY),
+                      std::less<double>());
+  TestBinaryCompareOp(javascript_.LessThan(LanguageMode::STRONG),
+                      std::less<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSLessThanOrEqual) {
+  TestBinaryCompareOp(javascript_.LessThanOrEqual(LanguageMode::SLOPPY),
+                      std::less_equal<double>());
+  TestBinaryCompareOp(javascript_.LessThanOrEqual(LanguageMode::STRONG),
+                      std::less_equal<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSGreaterThan) {
+  TestBinaryCompareOp(javascript_.GreaterThan(LanguageMode::SLOPPY),
+                      std::greater<double>());
+  TestBinaryCompareOp(javascript_.GreaterThan(LanguageMode::STRONG),
+                      std::greater<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSGreaterThanOrEqual) {
+  TestBinaryCompareOp(javascript_.GreaterThanOrEqual(LanguageMode::SLOPPY),
+                      std::greater_equal<double>());
+  TestBinaryCompareOp(javascript_.GreaterThanOrEqual(LanguageMode::STRONG),
+                      std::greater_equal<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSEqual) {
+  TestBinaryCompareOp(javascript_.Equal(), std::equal_to<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSNotEqual) {
+  TestBinaryCompareOp(javascript_.NotEqual(), std::not_equal_to<double>());
+}
+
+
+// For numbers there's no difference between strict and non-strict equality.
+TEST_F(TyperTest, TypeJSStrictEqual) {
+  TestBinaryCompareOp(javascript_.StrictEqual(), std::equal_to<double>());
+}
+
+
+TEST_F(TyperTest, TypeJSStrictNotEqual) {
+  TestBinaryCompareOp(javascript_.StrictNotEqual(),
+                      std::not_equal_to<double>());
+}
+
+
+//------------------------------------------------------------------------------
+// Monotonicity
+
+
+#define TEST_BINARY_MONOTONICITY(name)          \
+  TEST_F(TyperTest, Monotonicity_##name) {      \
+    TestBinaryMonotonicity(javascript_.name()); \
+  }
+TEST_BINARY_MONOTONICITY(Equal)
+TEST_BINARY_MONOTONICITY(NotEqual)
+TEST_BINARY_MONOTONICITY(StrictEqual)
+TEST_BINARY_MONOTONICITY(StrictNotEqual)
+#undef TEST_BINARY_MONOTONICITY
+
+
+#define TEST_BINARY_MONOTONICITY(name)                              \
+  TEST_F(TyperTest, Monotonicity_##name) {                          \
+    TestBinaryMonotonicity(javascript_.name(LanguageMode::SLOPPY)); \
+    TestBinaryMonotonicity(javascript_.name(LanguageMode::STRONG)); \
+  }
+TEST_BINARY_MONOTONICITY(LessThan)
+TEST_BINARY_MONOTONICITY(GreaterThan)
+TEST_BINARY_MONOTONICITY(LessThanOrEqual)
+TEST_BINARY_MONOTONICITY(GreaterThanOrEqual)
+#undef TEST_BINARY_MONOTONICITY
+
+
+#define TEST_BINARY_MONOTONICITY(name)                                        \
+  TEST_F(TyperTest, Monotonicity_##name) {                                    \
+    TestBinaryMonotonicity(                                                   \
+        javascript_.name(LanguageMode::SLOPPY, BinaryOperationHints::Any())); \
+    TestBinaryMonotonicity(                                                   \
+        javascript_.name(LanguageMode::STRONG, BinaryOperationHints::Any())); \
+  }
+TEST_BINARY_MONOTONICITY(BitwiseOr)
+TEST_BINARY_MONOTONICITY(BitwiseXor)
+TEST_BINARY_MONOTONICITY(BitwiseAnd)
+TEST_BINARY_MONOTONICITY(ShiftLeft)
+TEST_BINARY_MONOTONICITY(ShiftRight)
+TEST_BINARY_MONOTONICITY(ShiftRightLogical)
+TEST_BINARY_MONOTONICITY(Add)
+TEST_BINARY_MONOTONICITY(Subtract)
+TEST_BINARY_MONOTONICITY(Multiply)
+TEST_BINARY_MONOTONICITY(Divide)
+TEST_BINARY_MONOTONICITY(Modulus)
+#undef TEST_BINARY_MONOTONICITY
+
+
+//------------------------------------------------------------------------------
+// Regression tests
+
+
+TEST_F(TyperTest, TypeRegressInt32Constant) {
+  int values[] = {-5, 10};
+  for (auto i : values) {
+    Node* c = graph()->NewNode(common()->Int32Constant(i));
+    Type* type = NodeProperties::GetType(c);
+    EXPECT_TRUE(type->Is(NewRange(i, i)));
+  }
+}
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8