diff --git a/caffe2/core/tensor.h b/caffe2/core/tensor.h
index 2fc13173954..ed57bec7349 100644
--- a/caffe2/core/tensor.h
+++ b/caffe2/core/tensor.h
@@ -160,7 +160,6 @@ class Tensor {
   template <class ContextForCopy>
   void Extend(TIndex num, float growthPct, ContextForCopy* context) {
     CAFFE_ENFORCE_GE(dims_.size(), 1);
-    auto oldSize = size_;
     auto newDims = dims_;
     newDims[0] += num;
     if (!data_) {
@@ -169,20 +168,37 @@ class Tensor {
     }
     auto newSize = std::accumulate(
         newDims.begin(), newDims.end(), 1, std::multiplies<TIndex>());
-    if (newSize * meta_.itemsize() > capacity_) {
-      auto newCapacity = dims_;
-      newCapacity[0] = std::max<size_t>(
-          newDims[0], std::ceil(dims_[0] * (growthPct + 100) / 100));
-      auto oldData = std::move(data_);
-      Resize(newCapacity);
-      auto* newData = raw_mutable_data(meta_);
-      context->template CopyItems<ContextForCopy, ContextForCopy>(
-          meta_, oldSize, oldData.get(), newData);
+    if (newSize * meta_.itemsize() <= capacity_) {
+      dims_ = newDims;
+      size_ = newSize;
+      return;
     }
+    auto newCapacity = dims_;
+    newCapacity[0] = std::max<size_t>(
+        newDims[0], std::ceil(dims_[0] * (growthPct + 100) / 100));
+    Reserve(newCapacity, context);
     dims_ = newDims;
     size_ = newSize;
   }
 
+  template <class T, class ContextForCopy>
+  void Reserve(const std::vector<T>& newCapacity, ContextForCopy* context) {
+    auto newSize = std::accumulate(
+        newCapacity.begin(), newCapacity.end(), 1, std::multiplies<TIndex>());
+    if (newSize * meta_.itemsize() <= capacity_) {
+      return;
+    }
+    auto oldData = std::move(data_);
+    auto oldSize = size_;
+    auto oldDims = dims_;
+    Resize(newCapacity);
+    auto* newData = raw_mutable_data(meta_);
+    context->template CopyItems<ContextForCopy, ContextForCopy>(
+        meta_, oldSize, oldData.get(), newData);
+    dims_ = oldDims;
+    size_ = oldSize;
+  }
+
   /**
    * @brief Shrinks the outer-most dimension to given size, keeping the data.
    *