diff --git a/runtime/lambda/closure_builder.h b/runtime/lambda/closure_builder.h
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+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef ART_RUNTIME_LAMBDA_CLOSURE_BUILDER_H_
+#define ART_RUNTIME_LAMBDA_CLOSURE_BUILDER_H_
+
+#include "base/macros.h"
+#include "base/mutex.h"  // For Locks::mutator_lock_.
+#include "base/value_object.h"
+#include "lambda/shorty_field_type.h"
+
+#include <stdint.h>
+#include <vector>
+
+namespace art {
+class ArtMethod;  // forward declaration
+
+namespace mirror {
+class Object;  // forward declaration
+}  // namespace mirror
+
+namespace lambda {
+class ArtLambdaMethod;  // forward declaration
+
+// Build a closure by capturing variables one at a time.
+// When all variables have been marked captured, the closure can be created in-place into
+// a target memory address.
+//
+// The mutator lock must be held for the duration of the lifetime of this object,
+// since it needs to temporarily store heap references into an internal list.
+class ClosureBuilder : ValueObject {
+ public:
+  using ShortyTypeEnum = decltype(ShortyFieldType::kByte);
+
+
+  // Mark this primitive value to be captured as the specified type.
+  template <typename T, ShortyTypeEnum kShortyType>
+  void CaptureVariablePrimitive(T value);
+
+  // Mark this object reference to be captured.
+  void CaptureVariableObject(mirror::Object* object) SHARED_REQUIRES(Locks::mutator_lock_);
+
+  // Mark this lambda closure to be captured.
+  void CaptureVariableLambda(Closure* closure);
+
+  // Get the size (in bytes) of the closure.
+  // This size is used to be able to allocate memory large enough to write the closure into.
+  // Call 'CreateInPlace' to actually write the closure out.
+  size_t GetSize() const;
+
+  // Returns how many variables have been captured so far.
+  size_t GetCaptureCount() const;
+
+  // Creates a closure in-place and writes out the data into 'memory'.
+  // Memory must be at least 'GetSize' bytes large.
+  // All previously marked data to be captured is now written out.
+  Closure* CreateInPlace(void* memory, ArtLambdaMethod* target_method) const
+      SHARED_REQUIRES(Locks::mutator_lock_);
+
+  // Locks need to be held for entire lifetime of ClosureBuilder.
+  ClosureBuilder() SHARED_REQUIRES(Locks::mutator_lock_)
+  {}
+
+  // Locks need to be held for entire lifetime of ClosureBuilder.
+  ~ClosureBuilder() SHARED_REQUIRES(Locks::mutator_lock_)
+  {}
+
+ private:
+  // Initial size a closure starts out before any variables are written.
+  // Header size only.
+  static constexpr size_t kInitialSize = sizeof(ArtLambdaMethod*);
+
+  // Write a Closure's variables field from the captured variables.
+  // variables_size specified in bytes, and only includes enough room to write variables into.
+  // Returns the calculated actual size of the closure.
+  size_t WriteValues(ArtLambdaMethod* target_method,
+                     uint8_t variables[],
+                     size_t header_size,
+                     size_t variables_size) const SHARED_REQUIRES(Locks::mutator_lock_);
+
+  size_t size_ = kInitialSize;
+  bool is_dynamic_size_ = false;
+  std::vector<ShortyFieldTypeTraits::MaxType> values_;
+};
+
+}  // namespace lambda
+}  // namespace art
+
+#endif  // ART_RUNTIME_LAMBDA_CLOSURE_BUILDER_H_