diff --git a/libcxx/benchmarks/ContainerBenchmarks.hpp b/libcxx/benchmarks/ContainerBenchmarks.hpp
index 648617a9cd23..581d3c53e603 100644
--- a/libcxx/benchmarks/ContainerBenchmarks.hpp
+++ b/libcxx/benchmarks/ContainerBenchmarks.hpp
@@ -1,8 +1,18 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
 #ifndef BENCHMARK_CONTAINER_BENCHMARKS_HPP
 #define BENCHMARK_CONTAINER_BENCHMARKS_HPP
 
 #include <cassert>
 
+#include "Utilities.hpp"
 #include "benchmark/benchmark.h"
 
 namespace ContainerBenchmarks {
@@ -12,7 +22,7 @@ void BM_ConstructSize(benchmark::State& st, Container) {
   auto size = st.range(0);
   for (auto _ : st) {
     Container c(size);
-    benchmark::DoNotOptimize(c.data());
+    DoNotOptimizeData(c);
   }
 }
 
@@ -21,7 +31,7 @@ void BM_ConstructSizeValue(benchmark::State& st, Container, typename Container::
   const auto size = st.range(0);
   for (auto _ : st) {
     Container c(size, val);
-    benchmark::DoNotOptimize(c.data());
+    DoNotOptimizeData(c);
   }
 }
 
@@ -33,7 +43,7 @@ void BM_ConstructIterIter(benchmark::State& st, Container, GenInputs gen) {
     benchmark::DoNotOptimize(&in);
     while (st.KeepRunning()) {
         Container c(begin, end);
-        benchmark::DoNotOptimize(c.data());
+        DoNotOptimizeData(c);
     }
 }
 
diff --git a/libcxx/benchmarks/Utilities.hpp b/libcxx/benchmarks/Utilities.hpp
new file mode 100644
index 000000000000..1b25f746ddaf
--- /dev/null
+++ b/libcxx/benchmarks/Utilities.hpp
@@ -0,0 +1,33 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef BENCHMARK_UTILITIES_HPP
+#define BENCHMARK_UTILITIES_HPP
+
+#include <cassert>
+#include <type_traits>
+
+#include "benchmark/benchmark.h"
+
+namespace UtilitiesInternal {
+  template <class Container>
+  auto HaveDataImpl(int) -> decltype((std::declval<Container&>().data(), std::true_type{}));
+  template <class Container>
+  auto HaveDataImpl(long) -> std::false_type;
+  template <class T>
+  using HasData = decltype(HaveDataImpl<T>(0));
+} // namespace UtilitiesInternal
+
+template <class Container, std::enable_if_t<UtilitiesInternal::HasData<Container>::value>* = nullptr>
+void DoNotOptimizeData(Container &c) { benchmark::DoNotOptimize(c.data()); }
+template <class Container, std::enable_if_t<!UtilitiesInternal::HasData<Container>::value>* = nullptr>
+void DoNotOptimizeData(Container &c) { benchmark::DoNotOptimize(&c); }
+
+
+#endif // BENCHMARK_UTILITIES_HPP
diff --git a/libcxx/benchmarks/deque.bench.cpp b/libcxx/benchmarks/deque.bench.cpp
new file mode 100644
index 000000000000..44a492b7b3d1
--- /dev/null
+++ b/libcxx/benchmarks/deque.bench.cpp
@@ -0,0 +1,47 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <deque>
+
+#include "benchmark/benchmark.h"
+
+#include "ContainerBenchmarks.hpp"
+#include "GenerateInput.hpp"
+
+using namespace ContainerBenchmarks;
+
+constexpr std::size_t TestNumInputs = 1024;
+
+BENCHMARK_CAPTURE(BM_ConstructSize,
+    deque_byte,
+    std::deque<unsigned char>{})->Arg(5140480);
+
+BENCHMARK_CAPTURE(BM_ConstructSizeValue,
+    deque_byte,
+    std::deque<unsigned char>{}, 0)->Arg(5140480);
+
+BENCHMARK_CAPTURE(BM_ConstructIterIter,
+  deque_char,
+  std::deque<char>{},
+  getRandomIntegerInputs<char>)->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(BM_ConstructIterIter,
+  deque_size_t,
+  std::deque<size_t>{},
+  getRandomIntegerInputs<size_t>)->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(BM_ConstructIterIter,
+  deque_string,
+  std::deque<std::string>{},
+  getRandomStringInputs)->Arg(TestNumInputs);
+
+
+
+
+BENCHMARK_MAIN();
diff --git a/libcxx/include/__split_buffer b/libcxx/include/__split_buffer
index 1daa4e5ada3d..095fe8928c6d 100644
--- a/libcxx/include/__split_buffer
+++ b/libcxx/include/__split_buffer
@@ -161,6 +161,19 @@ private:
     _LIBCPP_INLINE_VISIBILITY
     void __move_assign_alloc(__split_buffer&, false_type) _NOEXCEPT
         {}
+
+    struct _ConstructTransaction {
+      explicit _ConstructTransaction(pointer* __p, size_type __n) _NOEXCEPT
+      : __pos_(*__p), __end_(*__p + __n), __dest_(__p) {
+      }
+      ~_ConstructTransaction() {
+        *__dest_ = __pos_;
+      }
+      pointer __pos_;
+     const pointer __end_;
+    private:
+     pointer *__dest_;
+    };
 };
 
 template <class _Tp, class _Allocator>
@@ -197,13 +210,10 @@ template <class _Tp, class _Allocator>
 void
 __split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n)
 {
-    __alloc_rr& __a = this->__alloc();
-    do
-    {
-        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_));
-        ++this->__end_;
-        --__n;
-    } while (__n > 0);
+    _ConstructTransaction __tx(&this->__end_, __n);
+    for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
+        __alloc_traits::construct(this->__alloc(), _VSTD::__to_raw_pointer(__tx.__pos_));
+    }
 }
 
 //  Copy constructs __n objects starting at __end_ from __x
@@ -216,13 +226,11 @@ template <class _Tp, class _Allocator>
 void
 __split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x)
 {
-    __alloc_rr& __a = this->__alloc();
-    do
-    {
-        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), __x);
-        ++this->__end_;
-        --__n;
-    } while (__n > 0);
+    _ConstructTransaction __tx(&this->__end_, __n);
+    for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
+        __alloc_traits::construct(this->__alloc(),
+            _VSTD::__to_raw_pointer(__tx.__pos_), __x);
+    }
 }
 
 template <class _Tp, class _Allocator>
@@ -262,11 +270,10 @@ typename enable_if
 >::type
 __split_buffer<_Tp, _Allocator>::__construct_at_end(_ForwardIterator __first, _ForwardIterator __last)
 {
-    __alloc_rr& __a = this->__alloc();
-    for (; __first != __last; ++__first)
-    {
-        __alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), *__first);
-        ++this->__end_;
+    _ConstructTransaction __tx(&this->__end_, std::distance(__first, __last));
+    for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, ++__first) {
+        __alloc_traits::construct(this->__alloc(),
+            _VSTD::__to_raw_pointer(__tx.__pos_), *__first);
     }
 }
 
diff --git a/libcxx/include/deque b/libcxx/include/deque
index fe988d093ef8..cb7e4e532719 100644
--- a/libcxx/include/deque
+++ b/libcxx/include/deque
@@ -956,6 +956,74 @@ public:
     typedef __deque_iterator<value_type, const_pointer, const_reference, __map_const_pointer,
                              difference_type>    const_iterator;
 
+    struct __deque_block_range {
+      explicit __deque_block_range(pointer __b, pointer __e) _NOEXCEPT : __begin_(__b), __end_(__e) {}
+      const pointer __begin_;
+      const pointer __end_;
+    };
+
+    struct __deque_range {
+      iterator __pos_;
+      const iterator __end_;
+
+      __deque_range(iterator __pos, iterator __e) _NOEXCEPT
+        : __pos_(__pos), __end_(__e) {}
+
+      explicit operator bool() const _NOEXCEPT {
+        return __pos_ != __end_;
+      }
+
+      __deque_range begin() const {
+        return *this;
+      }
+
+      __deque_range end() const {
+        return __deque_range(__end_, __end_);
+      }
+      __deque_block_range operator*() const _NOEXCEPT {
+         if (__pos_.__m_iter_ == __end_.__m_iter_) {
+          return __deque_block_range(__pos_.__ptr_, __end_.__ptr_);
+        }
+        return __deque_block_range(__pos_.__ptr_, *__pos_.__m_iter_ + __block_size);
+      }
+
+      __deque_range& operator++() _NOEXCEPT {
+        if (__pos_.__m_iter_ == __end_.__m_iter_) {
+          __pos_ = __end_;
+        } else {
+          ++__pos_.__m_iter_;
+          __pos_.__ptr_ = *__pos_.__m_iter_;
+        }
+        return *this;
+      }
+
+
+      friend bool operator==(__deque_range const& __lhs, __deque_range const& __rhs) {
+        return __lhs.__pos_ == __rhs.__pos_;
+      }
+      friend bool operator!=(__deque_range const& __lhs, __deque_range const& __rhs) {
+        return !(__lhs == __rhs);
+      }
+    };
+
+
+
+    struct _ConstructTransaction {
+      _ConstructTransaction(__deque_base* __db, __deque_block_range& __r)
+        : __pos_(__r.__begin_), __end_(__r.__end_), __begin_(__r.__begin_), __base_(__db) {}
+
+
+      ~_ConstructTransaction() {
+        __base_->size() += (__pos_ - __begin_);
+      }
+
+      pointer __pos_;
+      const pointer __end_;
+    private:
+      const pointer __begin_;
+      __deque_base * const __base_;
+    };
+
 protected:
     __map __map_;
     size_type __start_;
@@ -1222,6 +1290,10 @@ public:
     typedef _VSTD::reverse_iterator<iterator>       reverse_iterator;
     typedef _VSTD::reverse_iterator<const_iterator> const_reverse_iterator;
 
+    using typename __base::__deque_range;
+    using typename __base::__deque_block_range;
+    using typename __base::_ConstructTransaction;
+
     // construct/copy/destroy:
     _LIBCPP_INLINE_VISIBILITY
     deque()
@@ -2299,8 +2371,12 @@ deque<_Tp, _Allocator>::__append(_ForIter __f, _ForIter __l,
     if (__n > __back_capacity)
         __add_back_capacity(__n - __back_capacity);
     // __n <= __back_capacity
-    for (iterator __i = __base::end(); __f != __l; ++__i, (void) ++__f, ++__base::size())
-        __alloc_traits::construct(__a, _VSTD::addressof(*__i), *__f);
+    for (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
+      _ConstructTransaction __tx(this, __br);
+      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, (void)++__f) {
+        __alloc_traits::construct(__a, std::__to_raw_pointer(__tx.__pos_), *__f);
+      }
+    }
 }
 
 template <class _Tp, class _Allocator>
@@ -2312,8 +2388,12 @@ deque<_Tp, _Allocator>::__append(size_type __n)
     if (__n > __back_capacity)
         __add_back_capacity(__n - __back_capacity);
     // __n <= __back_capacity
-    for (iterator __i = __base::end(); __n; --__n, ++__i, ++__base::size())
-        __alloc_traits::construct(__a, _VSTD::addressof(*__i));
+    for (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
+      _ConstructTransaction __tx(this, __br);
+      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
+        __alloc_traits::construct(__a, std::__to_raw_pointer(__tx.__pos_));
+      }
+    }
 }
 
 template <class _Tp, class _Allocator>
@@ -2325,8 +2405,13 @@ deque<_Tp, _Allocator>::__append(size_type __n, const value_type& __v)
     if (__n > __back_capacity)
         __add_back_capacity(__n - __back_capacity);
     // __n <= __back_capacity
-    for (iterator __i = __base::end(); __n; --__n, ++__i, ++__base::size())
-        __alloc_traits::construct(__a, _VSTD::addressof(*__i), __v);
+    for (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
+      _ConstructTransaction __tx(this, __br);
+      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
+        __alloc_traits::construct(__a, std::__to_raw_pointer(__tx.__pos_), __v);
+      }
+    }
+
 }
 
 // Create front capacity for one block of elements.