diff --git a/src/signature.h b/src/signature.h
new file mode 100644
index 0000000..076d17a
--- /dev/null
+++ b/src/signature.h
@@ -0,0 +1,80 @@
+// 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.
+
+#ifndef V8_SIGNATURE_H_
+#define V8_SIGNATURE_H_
+
+#include "src/zone.h"
+
+namespace v8 {
+namespace internal {
+
+// Describes the inputs and outputs of a function or call.
+template <typename T>
+class Signature : public ZoneObject {
+ public:
+  Signature(size_t return_count, size_t parameter_count, T* reps)
+      : return_count_(return_count),
+        parameter_count_(parameter_count),
+        reps_(reps) {}
+
+  size_t return_count() const { return return_count_; }
+  size_t parameter_count() const { return parameter_count_; }
+
+  T GetParam(size_t index) const {
+    DCHECK(index < parameter_count_);
+    return reps_[return_count_ + index];
+  }
+
+  T GetReturn(size_t index = 0) const {
+    DCHECK(index < return_count_);
+    return reps_[index];
+  }
+
+  // For incrementally building signatures.
+  class Builder {
+   public:
+    Builder(Zone* zone, size_t return_count, size_t parameter_count)
+        : return_count_(return_count),
+          parameter_count_(parameter_count),
+          zone_(zone),
+          rcursor_(0),
+          pcursor_(0),
+          buffer_(zone->NewArray<T>(
+              static_cast<int>(return_count + parameter_count))) {}
+
+    const size_t return_count_;
+    const size_t parameter_count_;
+
+    void AddReturn(T val) {
+      DCHECK(rcursor_ < return_count_);
+      buffer_[rcursor_++] = val;
+    }
+    void AddParam(T val) {
+      DCHECK(pcursor_ < parameter_count_);
+      buffer_[return_count_ + pcursor_++] = val;
+    }
+    Signature<T>* Build() {
+      DCHECK(rcursor_ == return_count_);
+      DCHECK(pcursor_ == parameter_count_);
+      return new (zone_) Signature<T>(return_count_, parameter_count_, buffer_);
+    }
+
+   private:
+    Zone* zone_;
+    size_t rcursor_;
+    size_t pcursor_;
+    T* buffer_;
+  };
+
+ protected:
+  size_t return_count_;
+  size_t parameter_count_;
+  T* reps_;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_SIGNATURE_H_