diff --git a/CMakeLists.txt b/CMakeLists.txt
index c78dc41..54e5e3a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -440,10 +440,6 @@
 # they are used when checking for compiler features.
 set(CMAKE_REQUIRED_FLAGS ${CMAKE_CXX_FLAGS})
 
-# Set the Ceres option for C++11.
-# TODO(alex): Remove when #defines are removed from source & config.h
-list(APPEND CERES_COMPILE_OPTIONS CERES_STD_UNORDERED_MAP)
-
 if (TBB)
   find_package(TBB QUIET)
   if (TBB_FOUND)
diff --git a/cmake/config.h.in b/cmake/config.h.in
index 76b853c..d031651 100644
--- a/cmake/config.h.in
+++ b/cmake/config.h.in
@@ -73,13 +73,6 @@
 @CERES_HAVE_PTHREAD@
 @CERES_HAVE_RWLOCK@
 
-// Which version of unordered map was used when Ceres was compiled. Exactly
-// one of these will be defined for any given build.
-@CERES_STD_UNORDERED_MAP@
-@CERES_STD_UNORDERED_MAP_IN_TR1_NAMESPACE@
-@CERES_TR1_UNORDERED_MAP@
-@CERES_NO_UNORDERED_MAP@
-
 // If defined, the memory header is in <tr1/memory>, otherwise <memory>.
 @CERES_TR1_MEMORY_HEADER@
 
diff --git a/internal/ceres/block_random_access_diagonal_matrix.h b/internal/ceres/block_random_access_diagonal_matrix.h
index 07ffc9d..2a8340b 100644
--- a/internal/ceres/block_random_access_diagonal_matrix.h
+++ b/internal/ceres/block_random_access_diagonal_matrix.h
@@ -36,7 +36,6 @@
 #include <utility>
 #include "ceres/mutex.h"
 #include "ceres/block_random_access_matrix.h"
-#include "ceres/collections_port.h"
 #include "ceres/triplet_sparse_matrix.h"
 #include "ceres/integral_types.h"
 #include "ceres/internal/macros.h"
diff --git a/internal/ceres/block_random_access_sparse_matrix.cc b/internal/ceres/block_random_access_sparse_matrix.cc
index 5432ec1..540a8b9 100644
--- a/internal/ceres/block_random_access_sparse_matrix.cc
+++ b/internal/ceres/block_random_access_sparse_matrix.cc
@@ -69,11 +69,9 @@
   // object for looking into the values array of the
   // TripletSparseMatrix.
   int num_nonzeros = 0;
-  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
-       it != block_pairs.end();
-       ++it) {
-    const int row_block_size = blocks_[it->first];
-    const int col_block_size = blocks_[it->second];
+  for (const auto& block_pair : block_pairs) {
+    const int row_block_size = blocks_[block_pair.first];
+    const int col_block_size = blocks_[block_pair.second];
     num_nonzeros += row_block_size * col_block_size;
   }
 
@@ -88,24 +86,19 @@
   double* values = tsm_->mutable_values();
 
   int pos = 0;
-  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
-       it != block_pairs.end();
-       ++it) {
-    const int row_block_size = blocks_[it->first];
-    const int col_block_size = blocks_[it->second];
-    cell_values_.push_back(make_pair(make_pair(it->first, it->second),
-                                     values + pos));
-    layout_[IntPairToLong(it->first, it->second)] =
+  for (const auto& block_pair : block_pairs) {
+    const int row_block_size = blocks_[block_pair.first];
+    const int col_block_size = blocks_[block_pair.second];
+    cell_values_.push_back(make_pair(block_pair, values + pos));
+    layout_[IntPairToLong(block_pair.first, block_pair.second)] =
         new CellInfo(values + pos);
     pos += row_block_size * col_block_size;
   }
 
   // Fill the sparsity pattern of the underlying matrix.
-  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
-       it != block_pairs.end();
-       ++it) {
-    const int row_block_id = it->first;
-    const int col_block_id = it->second;
+  for (const auto& block_pair : block_pairs) {
+    const int row_block_id = block_pair.first;
+    const int col_block_id = block_pair.second;
     const int row_block_size = blocks_[row_block_id];
     const int col_block_size = blocks_[col_block_id];
     int pos =
@@ -125,10 +118,8 @@
 // Assume that the user does not hold any locks on any cell blocks
 // when they are calling SetZero.
 BlockRandomAccessSparseMatrix::~BlockRandomAccessSparseMatrix() {
-  for (LayoutType::iterator it = layout_.begin();
-       it != layout_.end();
-       ++it) {
-    delete it->second;
+  for (const auto& entry : layout_) {
+    delete entry.second;
   }
 }
 
@@ -163,19 +154,17 @@
 
 void BlockRandomAccessSparseMatrix::SymmetricRightMultiply(const double* x,
                                                            double* y) const {
-  vector< pair<pair<int, int>, double*> >::const_iterator it =
-      cell_values_.begin();
-  for (; it != cell_values_.end(); ++it) {
-    const int row = it->first.first;
+  for (const auto& cell_position_and_data : cell_values_) {
+    const int row = cell_position_and_data.first.first;
     const int row_block_size = blocks_[row];
     const int row_block_pos = block_positions_[row];
 
-    const int col = it->first.second;
+    const int col = cell_position_and_data.first.second;
     const int col_block_size = blocks_[col];
     const int col_block_pos = block_positions_[col];
 
     MatrixVectorMultiply<Eigen::Dynamic, Eigen::Dynamic, 1>(
-        it->second, row_block_size, col_block_size,
+        cell_position_and_data.second, row_block_size, col_block_size,
         x + col_block_pos,
         y + row_block_pos);
 
@@ -185,7 +174,7 @@
     // triangular multiply also.
     if (row != col) {
       MatrixTransposeVectorMultiply<Eigen::Dynamic, Eigen::Dynamic, 1>(
-          it->second, row_block_size, col_block_size,
+          cell_position_and_data.second, row_block_size, col_block_size,
           x + row_block_pos,
           y + col_block_pos);
     }
diff --git a/internal/ceres/block_random_access_sparse_matrix.h b/internal/ceres/block_random_access_sparse_matrix.h
index 2b3c7fd..e79667b 100644
--- a/internal/ceres/block_random_access_sparse_matrix.h
+++ b/internal/ceres/block_random_access_sparse_matrix.h
@@ -32,11 +32,11 @@
 #define CERES_INTERNAL_BLOCK_RANDOM_ACCESS_SPARSE_MATRIX_H_
 
 #include <set>
+#include <unordered_map>
 #include <vector>
 #include <utility>
 #include "ceres/mutex.h"
 #include "ceres/block_random_access_matrix.h"
-#include "ceres/collections_port.h"
 #include "ceres/triplet_sparse_matrix.h"
 #include "ceres/integral_types.h"
 #include "ceres/internal/macros.h"
@@ -109,7 +109,7 @@
 
   // A mapping from <row_block_id, col_block_id> to the position in
   // the values array of tsm_ where the block is stored.
-  typedef HashMap<long int, CellInfo* > LayoutType;
+  typedef std::unordered_map<long int, CellInfo* > LayoutType;
   LayoutType layout_;
 
   // In order traversal of contents of the matrix. This allows us to
diff --git a/internal/ceres/block_random_access_sparse_matrix_test.cc b/internal/ceres/block_random_access_sparse_matrix_test.cc
index e4d82d0..688b09d 100644
--- a/internal/ceres/block_random_access_sparse_matrix_test.cc
+++ b/internal/ceres/block_random_access_sparse_matrix_test.cc
@@ -68,11 +68,9 @@
   EXPECT_EQ(m.num_rows(), num_rows);
   EXPECT_EQ(m.num_cols(), num_rows);
 
-  for (set<pair<int, int> >::const_iterator it = block_pairs.begin();
-       it != block_pairs.end();
-       ++it) {
-    const int row_block_id = it->first;
-    const int col_block_id = it->second;
+  for (const auto& block_pair : block_pairs) {
+    const int row_block_id = block_pair.first;
+    const int col_block_id = block_pair.second;
     int row;
     int col;
     int row_stride;
diff --git a/internal/ceres/canonical_views_clustering.cc b/internal/ceres/canonical_views_clustering.cc
index b3e9c22..ca8dff5 100644
--- a/internal/ceres/canonical_views_clustering.cc
+++ b/internal/ceres/canonical_views_clustering.cc
@@ -31,7 +31,9 @@
 
 #include "ceres/canonical_views_clustering.h"
 
-#include "ceres/collections_port.h"
+#include <unordered_set>
+#include <unordered_map>
+
 #include "ceres/graph.h"
 #include "ceres/internal/macros.h"
 #include "ceres/map_util.h"
@@ -42,8 +44,8 @@
 
 using std::vector;
 
-typedef HashMap<int, int> IntMap;
-typedef HashSet<int> IntSet;
+typedef std::unordered_map<int, int> IntMap;
+typedef std::unordered_set<int> IntSet;
 
 class CanonicalViewsClustering {
  public:
@@ -76,7 +78,7 @@
   // center).
   IntMap view_to_canonical_view_;
   // Maps a view to its similarity to its current cluster center.
-  HashMap<int, double> view_to_canonical_view_similarity_;
+  std::unordered_map<int, double> view_to_canonical_view_similarity_;
   CERES_DISALLOW_COPY_AND_ASSIGN(CanonicalViewsClustering);
 };
 
@@ -111,14 +113,12 @@
     int best_view = 0;
 
     // TODO(sameeragarwal): Make this loop multi-threaded.
-    for (IntSet::const_iterator view = valid_views.begin();
-         view != valid_views.end();
-         ++view) {
+    for (const auto& view : valid_views) {
       const double difference =
-          ComputeClusteringQualityDifference(*view, *centers);
+          ComputeClusteringQualityDifference(view, *centers);
       if (difference > best_difference) {
         best_difference = difference;
-        best_view = *view;
+        best_view = view;
       }
     }
 
@@ -144,11 +144,9 @@
 void CanonicalViewsClustering::FindValidViews(
     IntSet* valid_views) const {
   const IntSet& views = graph_->vertices();
-  for (IntSet::const_iterator view = views.begin();
-       view != views.end();
-       ++view) {
-    if (graph_->VertexWeight(*view) != WeightedGraph<int>::InvalidWeight()) {
-      valid_views->insert(*view);
+  for (const auto& view : views) {
+    if (graph_->VertexWeight(view) != WeightedGraph<int>::InvalidWeight()) {
+      valid_views->insert(view);
     }
   }
 }
@@ -166,12 +164,10 @@
   // was added to the list of canonical views and its nearest
   // neighbors became members of its cluster.
   const IntSet& neighbors = graph_->Neighbors(candidate);
-  for (IntSet::const_iterator neighbor = neighbors.begin();
-       neighbor != neighbors.end();
-       ++neighbor) {
+  for (const auto& neighbor : neighbors) {
     const double old_similarity =
-        FindWithDefault(view_to_canonical_view_similarity_, *neighbor, 0.0);
-    const double new_similarity = graph_->EdgeWeight(*neighbor, candidate);
+        FindWithDefault(view_to_canonical_view_similarity_, neighbor, 0.0);
+    const double new_similarity = graph_->EdgeWeight(neighbor, candidate);
     if (new_similarity > old_similarity) {
       difference += new_similarity - old_similarity;
     }
@@ -193,16 +189,14 @@
 void CanonicalViewsClustering::UpdateCanonicalViewAssignments(
     const int canonical_view) {
   const IntSet& neighbors = graph_->Neighbors(canonical_view);
-  for (IntSet::const_iterator neighbor = neighbors.begin();
-       neighbor != neighbors.end();
-       ++neighbor) {
+  for (const auto& neighbor : neighbors) {
     const double old_similarity =
-        FindWithDefault(view_to_canonical_view_similarity_, *neighbor, 0.0);
+        FindWithDefault(view_to_canonical_view_similarity_, neighbor, 0.0);
     const double new_similarity =
-        graph_->EdgeWeight(*neighbor, canonical_view);
+        graph_->EdgeWeight(neighbor, canonical_view);
     if (new_similarity > old_similarity) {
-      view_to_canonical_view_[*neighbor] = canonical_view;
-      view_to_canonical_view_similarity_[*neighbor] = new_similarity;
+      view_to_canonical_view_[neighbor] = canonical_view;
+      view_to_canonical_view_similarity_[neighbor] = new_similarity;
     }
   }
 }
@@ -222,17 +216,14 @@
   static const int kInvalidClusterId = -1;
 
   const IntSet& views = graph_->vertices();
-  for (IntSet::const_iterator view = views.begin();
-       view != views.end();
-       ++view) {
-    IntMap::const_iterator it =
-        view_to_canonical_view_.find(*view);
+  for (const auto& view : views) {
+    auto it = view_to_canonical_view_.find(view);
     int cluster_id = kInvalidClusterId;
     if (it != view_to_canonical_view_.end()) {
       cluster_id = FindOrDie(center_to_cluster_id, it->second);
     }
 
-    InsertOrDie(membership, *view, cluster_id);
+    InsertOrDie(membership, view, cluster_id);
   }
 }
 
diff --git a/internal/ceres/canonical_views_clustering.h b/internal/ceres/canonical_views_clustering.h
index 0847f48..6514827 100644
--- a/internal/ceres/canonical_views_clustering.h
+++ b/internal/ceres/canonical_views_clustering.h
@@ -41,9 +41,9 @@
 #ifndef CERES_INTERNAL_CANONICAL_VIEWS_CLUSTERING_H_
 #define CERES_INTERNAL_CANONICAL_VIEWS_CLUSTERING_H_
 
+#include <unordered_map>
 #include <vector>
 
-#include "ceres/collections_port.h"
 #include "ceres/graph.h"
 
 namespace ceres {
@@ -98,7 +98,7 @@
     const CanonicalViewsClusteringOptions& options,
     const WeightedGraph<int>& graph,
     std::vector<int>* centers,
-    HashMap<int, int>* membership);
+    std::unordered_map<int, int>* membership);
 
 struct CanonicalViewsClusteringOptions {
   CanonicalViewsClusteringOptions()
diff --git a/internal/ceres/canonical_views_clustering_test.cc b/internal/ceres/canonical_views_clustering_test.cc
index 0c15fc7..a8db293 100644
--- a/internal/ceres/canonical_views_clustering_test.cc
+++ b/internal/ceres/canonical_views_clustering_test.cc
@@ -31,7 +31,7 @@
 
 #include "ceres/canonical_views_clustering.h"
 
-#include "ceres/collections_port.h"
+#include <unordered_map>
 #include "ceres/graph.h"
 #include "gtest/gtest.h"
 
@@ -74,7 +74,7 @@
 
   CanonicalViewsClusteringOptions options_;
   std::vector<int> centers_;
-  HashMap<int, int> membership_;
+  std::unordered_map<int, int> membership_;
 };
 
 TEST_F(CanonicalViewsTest, ComputeCanonicalViewsTest) {
diff --git a/internal/ceres/collections_port.h b/internal/ceres/collections_port.h
deleted file mode 100644
index e699a66..0000000
--- a/internal/ceres/collections_port.h
+++ /dev/null
@@ -1,196 +0,0 @@
-// Ceres Solver - A fast non-linear least squares minimizer
-// Copyright 2015 Google Inc. All rights reserved.
-// http://ceres-solver.org/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are met:
-//
-// * Redistributions of source code must retain the above copyright notice,
-//   this list of conditions and the following disclaimer.
-// * Redistributions in binary form must reproduce the above copyright notice,
-//   this list of conditions and the following disclaimer in the documentation
-//   and/or other materials provided with the distribution.
-// * Neither the name of Google Inc. nor the names of its contributors may be
-//   used to endorse or promote products derived from this software without
-//   specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
-// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-// POSSIBILITY OF SUCH DAMAGE.
-//
-// Author: keir@google.com (Keir Mierle)
-//
-// Portable HashMap and HashSet, and a specialized overload for hashing pairs.
-
-#ifndef CERES_INTERNAL_COLLECTIONS_PORT_H_
-#define CERES_INTERNAL_COLLECTIONS_PORT_H_
-
-#include "ceres/internal/port.h"
-
-#if defined(CERES_NO_UNORDERED_MAP)
-#  include <map>
-#  include <set>
-#endif
-
-#if defined(CERES_TR1_UNORDERED_MAP)
-#  include <tr1/unordered_map>
-#  include <tr1/unordered_set>
-#  define CERES_HASH_NAMESPACE_START namespace std { namespace tr1 {
-#  define CERES_HASH_NAMESPACE_END } }
-#endif
-
-#if defined(CERES_STD_UNORDERED_MAP)
-#  include <unordered_map>
-#  include <unordered_set>
-#  define CERES_HASH_NAMESPACE_START namespace std {
-#  define CERES_HASH_NAMESPACE_END }
-#endif
-
-#if defined(CERES_STD_UNORDERED_MAP_IN_TR1_NAMESPACE)
-#  include <unordered_map>
-#  include <unordered_set>
-#  define CERES_HASH_NAMESPACE_START namespace std { namespace tr1 {
-#  define CERES_HASH_NAMESPACE_END } }
-#endif
-
-#if !defined(CERES_NO_UNORDERED_MAP) && !defined(CERES_TR1_UNORDERED_MAP) && \
-    !defined(CERES_STD_UNORDERED_MAP) && !defined(CERES_STD_UNORDERED_MAP_IN_TR1_NAMESPACE)  // NOLINT
-#  error One of: CERES_NO_UNORDERED_MAP, CERES_TR1_UNORDERED_MAP,\
- CERES_STD_UNORDERED_MAP, CERES_STD_UNORDERED_MAP_IN_TR1_NAMESPACE must be defined!  // NOLINT
-#endif
-
-#include <utility>
-#include "ceres/integral_types.h"
-
-// Some systems don't have access to unordered_map/unordered_set. In
-// that case, substitute the hash map/set with normal map/set. The
-// price to pay is slower speed for some operations.
-#if defined(CERES_NO_UNORDERED_MAP)
-
-namespace ceres {
-namespace internal {
-
-template<typename K, typename V>
-struct HashMap : map<K, V> {};
-
-template<typename K>
-struct HashSet : set<K> {};
-
-}  // namespace internal
-}  // namespace ceres
-
-#else
-
-namespace ceres {
-namespace internal {
-
-#if defined(CERES_TR1_UNORDERED_MAP) || \
-    defined(CERES_STD_UNORDERED_MAP_IN_TR1_NAMESPACE)
-template<typename K, typename V>
-struct HashMap : std::tr1::unordered_map<K, V> {};
-template<typename K>
-struct HashSet : std::tr1::unordered_set<K> {};
-#endif
-
-#if defined(CERES_STD_UNORDERED_MAP)
-template<typename K, typename V>
-struct HashMap : std::unordered_map<K, V> {};
-template<typename K>
-struct HashSet : std::unordered_set<K> {};
-#endif
-
-#if defined(_WIN32) && !defined(__MINGW64__) && !defined(__MINGW32__)
-#define GG_LONGLONG(x) x##I64
-#define GG_ULONGLONG(x) x##UI64
-#else
-#define GG_LONGLONG(x) x##LL
-#define GG_ULONGLONG(x) x##ULL
-#endif
-
-// The hash function is due to Bob Jenkins (see
-// http://burtleburtle.net/bob/hash/index.html). Each mix takes 36 instructions,
-// in 18 cycles if you're lucky. On x86 architectures, this requires 45
-// instructions in 27 cycles, if you're lucky.
-//
-// 32bit version
-inline void hash_mix(uint32& a, uint32& b, uint32& c) {
-  a -= b; a -= c; a ^= (c>>13);
-  b -= c; b -= a; b ^= (a<<8);
-  c -= a; c -= b; c ^= (b>>13);
-  a -= b; a -= c; a ^= (c>>12);
-  b -= c; b -= a; b ^= (a<<16);
-  c -= a; c -= b; c ^= (b>>5);
-  a -= b; a -= c; a ^= (c>>3);
-  b -= c; b -= a; b ^= (a<<10);
-  c -= a; c -= b; c ^= (b>>15);
-}
-
-// 64bit version
-inline void hash_mix(uint64& a, uint64& b, uint64& c) {
-  a -= b; a -= c; a ^= (c>>43);
-  b -= c; b -= a; b ^= (a<<9);
-  c -= a; c -= b; c ^= (b>>8);
-  a -= b; a -= c; a ^= (c>>38);
-  b -= c; b -= a; b ^= (a<<23);
-  c -= a; c -= b; c ^= (b>>5);
-  a -= b; a -= c; a ^= (c>>35);
-  b -= c; b -= a; b ^= (a<<49);
-  c -= a; c -= b; c ^= (b>>11);
-}
-
-inline uint32 Hash32NumWithSeed(uint32 num, uint32 c) {
-  // The golden ratio; an arbitrary value.
-  uint32 b = 0x9e3779b9UL;
-  hash_mix(num, b, c);
-  return c;
-}
-
-inline uint64 Hash64NumWithSeed(uint64 num, uint64 c) {
-  // More of the golden ratio.
-  uint64 b = GG_ULONGLONG(0xe08c1d668b756f82);
-  hash_mix(num, b, c);
-  return c;
-}
-
-}  // namespace internal
-}  // namespace ceres
-
-// Since on some platforms this is a doubly-nested namespace (std::tr1) and
-// others it is not, the entire namespace line must be in a macro.
-CERES_HASH_NAMESPACE_START
-
-// The outrageously annoying specializations below are for portability reasons.
-// In short, it's not possible to have two overloads of hash<pair<T1, T2>
-
-// Hasher for STL pairs. Requires hashers for both members to be defined.
-template<typename T>
-struct hash<pair<T, T> > {
-  size_t operator()(const pair<T, T>& p) const {
-    size_t h1 = hash<T>()(p.first);
-    size_t h2 = hash<T>()(p.second);
-    // The decision below is at compile time
-    return (sizeof(h1) <= sizeof(ceres::internal::uint32)) ?
-            ceres::internal::Hash32NumWithSeed(h1, h2) :
-            ceres::internal::Hash64NumWithSeed(h1, h2);
-  }
-  // Less than operator for MSVC.
-  bool operator()(const pair<T, T>& a,
-                  const pair<T, T>& b) const {
-    return a < b;
-  }
-  static const size_t bucket_size = 4;  // These are required by MSVC
-  static const size_t min_buckets = 8;  // 4 and 8 are defaults.
-};
-
-CERES_HASH_NAMESPACE_END
-
-#endif  // CERES_NO_UNORDERED_MAP
-#endif  // CERES_INTERNAL_COLLECTIONS_PORT_H_
diff --git a/internal/ceres/coordinate_descent_minimizer.cc b/internal/ceres/coordinate_descent_minimizer.cc
index a334dde..e5569d4 100644
--- a/internal/ceres/coordinate_descent_minimizer.cc
+++ b/internal/ceres/coordinate_descent_minimizer.cc
@@ -80,18 +80,15 @@
   // offsets for parallel access.
   map<ParameterBlock*, int> parameter_block_index;
   map<int, set<double*> > group_to_elements = ordering.group_to_elements();
-  for (map<int, set<double*> >::const_iterator it = group_to_elements.begin();
-       it != group_to_elements.end();
-       ++it) {
-    for (set<double*>::const_iterator ptr_it = it->second.begin();
-         ptr_it != it->second.end();
-         ++ptr_it) {
-      parameter_blocks_.push_back(parameter_map.find(*ptr_it)->second);
+  for (const auto& g_t_e : group_to_elements) {
+    const auto& elements = g_t_e.second;
+    for (double* parameter_block: elements) {
+      parameter_blocks_.push_back(parameter_map.find(parameter_block)->second);
       parameter_block_index[parameter_blocks_.back()] =
           parameter_blocks_.size() - 1;
     }
     independent_set_offsets_.push_back(
-        independent_set_offsets_.back() + it->second.size());
+        independent_set_offsets_.back() + elements.size());
   }
 
   // The ordering does not have to contain all parameter blocks, so
@@ -114,8 +111,7 @@
     const int num_parameter_blocks = residual_block->NumParameterBlocks();
     for (int j = 0; j < num_parameter_blocks; ++j) {
       ParameterBlock* parameter_block = residual_block->parameter_blocks()[j];
-      const map<ParameterBlock*, int>::const_iterator it =
-          parameter_block_index.find(parameter_block);
+      const auto it = parameter_block_index.find(parameter_block);
       if (it != parameter_block_index.end()) {
         residual_blocks_[it->second].push_back(residual_block);
       }
@@ -267,13 +263,12 @@
       ordering.group_to_elements();
 
   // Verify that each group is an independent set
-  map<int, set<double*> >::const_iterator it = group_to_elements.begin();
-  for (; it != group_to_elements.end(); ++it) {
-    if (!program.IsParameterBlockSetIndependent(it->second)) {
+  for (const auto& g_t_e : group_to_elements) {
+    if (!program.IsParameterBlockSetIndependent(g_t_e.second)) {
       *message =
           StringPrintf("The user-provided "
                        "parameter_blocks_for_inner_iterations does not "
-                       "form an independent set. Group Id: %d", it->first);
+                       "form an independent set. Group Id: %d", g_t_e.first);
       return false;
     }
   }
diff --git a/internal/ceres/covariance_impl.cc b/internal/ceres/covariance_impl.cc
index c52866b..484c94f 100644
--- a/internal/ceres/covariance_impl.cc
+++ b/internal/ceres/covariance_impl.cc
@@ -38,6 +38,7 @@
 #include <cstdlib>
 #include <numeric>
 #include <sstream>
+#include <unordered_set>
 #include <utility>
 #include <vector>
 
@@ -45,7 +46,6 @@
 #include "Eigen/SparseQR"
 #include "Eigen/SVD"
 
-#include "ceres/collections_port.h"
 #include "ceres/compressed_col_sparse_matrix_utils.h"
 #include "ceres/compressed_row_sparse_matrix.h"
 #include "ceres/covariance.h"
@@ -412,7 +412,7 @@
   vector<double*> all_parameter_blocks;
   problem->GetParameterBlocks(&all_parameter_blocks);
   const ProblemImpl::ParameterMap& parameter_map = problem->parameter_map();
-  HashSet<ParameterBlock*> parameter_blocks_in_use;
+  std::unordered_set<ParameterBlock*> parameter_blocks_in_use;
   vector<ResidualBlock*> residual_blocks;
   problem->GetResidualBlocks(&residual_blocks);
 
@@ -511,13 +511,10 @@
   // rows of the covariance matrix in order.
   int i = 0;  // index into covariance_blocks.
   int cursor = 0;  // index into the covariance matrix.
-  for (map<const double*, int>::const_iterator it =
-           parameter_block_to_row_index_.begin();
-       it != parameter_block_to_row_index_.end();
-       ++it) {
-    const double* row_block =  it->first;
+  for (const auto& entry : parameter_block_to_row_index_) {
+    const double* row_block =  entry.first;
     const int row_block_size = problem->ParameterBlockLocalSize(row_block);
-    int row_begin = it->second;
+    int row_begin = entry.second;
 
     // Iterate over the covariance blocks contained in this row block
     // and count the number of columns in this row block.
diff --git a/internal/ceres/covariance_test.cc b/internal/ceres/covariance_test.cc
index 92a7626..96c962a 100644
--- a/internal/ceres/covariance_test.cc
+++ b/internal/ceres/covariance_test.cc
@@ -564,9 +564,8 @@
     }
 
     int dof = 0;  // degrees of freedom = sum of LocalSize()s
-    for (BoundsMap::const_iterator iter = column_bounds.begin();
-         iter != column_bounds.end(); ++iter) {
-      dof = std::max(dof, iter->second.second);
+    for (const auto& bound : column_bounds) {
+      dof = std::max(dof, bound.second.second);
     }
     ConstMatrixRef expected(expected_covariance, dof, dof);
     double diff_norm = (expected.block(row_begin,
diff --git a/internal/ceres/graph.h b/internal/ceres/graph.h
index b96b672..25bb141 100644
--- a/internal/ceres/graph.h
+++ b/internal/ceres/graph.h
@@ -32,11 +32,12 @@
 #define CERES_INTERNAL_GRAPH_H_
 
 #include <limits>
+#include <unordered_set>
+#include <unordered_map>
 #include <utility>
 #include "ceres/integral_types.h"
 #include "ceres/map_util.h"
-#include "ceres/collections_port.h"
-#include "ceres/internal/macros.h"
+#include "ceres/pair_hash.h"
 #include "ceres/types.h"
 #include "glog/logging.h"
 
@@ -53,7 +54,7 @@
   // Add a vertex.
   void AddVertex(const Vertex& vertex) {
     if (vertices_.insert(vertex).second) {
-      edges_[vertex] = HashSet<Vertex>();
+      edges_[vertex] = std::unordered_set<Vertex>();
     }
   }
 
@@ -63,10 +64,9 @@
     }
 
     vertices_.erase(vertex);
-    const HashSet<Vertex>& sinks = edges_[vertex];
-    for (typename HashSet<Vertex>::const_iterator it = sinks.begin();
-         it != sinks.end(); ++it) {
-      edges_[*it].erase(vertex);
+    const std::unordered_set<Vertex>& sinks = edges_[vertex];
+    for (const Vertex& s : sinks) {
+      edges_[s].erase(vertex);
     }
 
     edges_.erase(vertex);
@@ -90,19 +90,17 @@
 
   // Calling Neighbors on a vertex not in the graph will result in
   // undefined behaviour.
-  const HashSet<Vertex>& Neighbors(const Vertex& vertex) const {
+  const std::unordered_set<Vertex>& Neighbors(const Vertex& vertex) const {
     return FindOrDie(edges_, vertex);
   }
 
-  const HashSet<Vertex>& vertices() const {
+  const std::unordered_set<Vertex>& vertices() const {
     return vertices_;
   }
 
  private:
-  HashSet<Vertex> vertices_;
-  HashMap<Vertex, HashSet<Vertex> > edges_;
-
-  CERES_DISALLOW_COPY_AND_ASSIGN(Graph);
+  std::unordered_set<Vertex> vertices_;
+  std::unordered_map<Vertex, std::unordered_set<Vertex> > edges_;
 };
 
 // A weighted undirected graph templated over the vertex ids. Vertex
@@ -117,7 +115,7 @@
   void AddVertex(const Vertex& vertex, double weight) {
     if (vertices_.find(vertex) == vertices_.end()) {
       vertices_.insert(vertex);
-      edges_[vertex] = HashSet<Vertex>();
+      edges_[vertex] = std::unordered_set<Vertex>();
     }
     vertex_weights_[vertex] = weight;
   }
@@ -135,15 +133,14 @@
 
     vertices_.erase(vertex);
     vertex_weights_.erase(vertex);
-    const HashSet<Vertex>& sinks = edges_[vertex];
-    for (typename HashSet<Vertex>::const_iterator it = sinks.begin();
-         it != sinks.end(); ++it) {
-      if (vertex < *it) {
-        edge_weights_.erase(std::make_pair(vertex, *it));
+    const std::unordered_set<Vertex>& sinks = edges_[vertex];
+    for (const Vertex& s : sinks) {
+      if (vertex < s) {
+        edge_weights_.erase(std::make_pair(vertex, s));
       } else {
-        edge_weights_.erase(std::make_pair(*it, vertex));
+        edge_weights_.erase(std::make_pair(s, vertex));
       }
-      edges_[*it].erase(vertex);
+      edges_[s].erase(vertex);
     }
 
     edges_.erase(vertex);
@@ -198,11 +195,11 @@
 
   // Calling Neighbors on a vertex not in the graph will result in
   // undefined behaviour.
-  const HashSet<Vertex>& Neighbors(const Vertex& vertex) const {
+  const std::unordered_set<Vertex>& Neighbors(const Vertex& vertex) const {
     return FindOrDie(edges_, vertex);
   }
 
-  const HashSet<Vertex>& vertices() const {
+  const std::unordered_set<Vertex>& vertices() const {
     return vertices_;
   }
 
@@ -211,12 +208,11 @@
   }
 
  private:
-  HashSet<Vertex> vertices_;
-  HashMap<Vertex, double> vertex_weights_;
-  HashMap<Vertex, HashSet<Vertex> > edges_;
-  HashMap<std::pair<Vertex, Vertex>, double> edge_weights_;
-
-  CERES_DISALLOW_COPY_AND_ASSIGN(WeightedGraph);
+  std::unordered_set<Vertex> vertices_;
+  std::unordered_map<Vertex, double> vertex_weights_;
+  std::unordered_map<Vertex, std::unordered_set<Vertex>> edges_;
+  std::unordered_map<std::pair<Vertex, Vertex>, double, pair_hash>
+      edge_weights_;
 };
 
 }  // namespace internal
diff --git a/internal/ceres/graph_algorithms.h b/internal/ceres/graph_algorithms.h
index d1d3f52..08837cf 100644
--- a/internal/ceres/graph_algorithms.h
+++ b/internal/ceres/graph_algorithms.h
@@ -34,9 +34,10 @@
 #define CERES_INTERNAL_GRAPH_ALGORITHMS_H_
 
 #include <algorithm>
+#include <unordered_map>
+#include <unordered_set>
 #include <vector>
 #include <utility>
-#include "ceres/collections_port.h"
 #include "ceres/graph.h"
 #include "ceres/wall_time.h"
 #include "glog/logging.h"
@@ -96,7 +97,7 @@
 template <typename Vertex>
 int IndependentSetOrdering(const Graph<Vertex>& graph,
                            std::vector<Vertex>* ordering) {
-  const HashSet<Vertex>& vertices = graph.vertices();
+  const std::unordered_set<Vertex>& vertices = graph.vertices();
   const int num_vertices = vertices.size();
 
   CHECK_NOTNULL(ordering);
@@ -109,34 +110,29 @@
   const char kBlack = 2;
 
   // Mark all vertices white.
-  HashMap<Vertex, char> vertex_color;
+  std::unordered_map<Vertex, char> vertex_color;
   std::vector<Vertex> vertex_queue;
-  for (typename HashSet<Vertex>::const_iterator it = vertices.begin();
-       it != vertices.end();
-       ++it) {
-    vertex_color[*it] = kWhite;
-    vertex_queue.push_back(*it);
+  for (const Vertex& vertex : vertices) {
+    vertex_color[vertex] = kWhite;
+    vertex_queue.push_back(vertex);
   }
 
-
-  std::sort(vertex_queue.begin(), vertex_queue.end(),
+  std::sort(vertex_queue.begin(),
+            vertex_queue.end(),
             VertexTotalOrdering<Vertex>(graph));
 
   // Iterate over vertex_queue. Pick the first white vertex, add it
   // to the independent set. Mark it black and its neighbors grey.
-  for (int i = 0; i < vertex_queue.size(); ++i) {
-    const Vertex& vertex = vertex_queue[i];
+  for (const Vertex& vertex : vertex_queue) {
     if (vertex_color[vertex] != kWhite) {
       continue;
     }
 
     ordering->push_back(vertex);
     vertex_color[vertex] = kBlack;
-    const HashSet<Vertex>& neighbors = graph.Neighbors(vertex);
-    for (typename HashSet<Vertex>::const_iterator it = neighbors.begin();
-         it != neighbors.end();
-         ++it) {
-      vertex_color[*it] = kGrey;
+    const std::unordered_set<Vertex>& neighbors = graph.Neighbors(vertex);
+    for (const Vertex& neighbor : neighbors) {
+      vertex_color[neighbor] = kGrey;
     }
   }
 
@@ -145,10 +141,7 @@
   // Iterate over the vertices and add all the grey vertices to the
   // ordering. At this stage there should only be black or grey
   // vertices in the graph.
-  for (typename std::vector<Vertex>::const_iterator it = vertex_queue.begin();
-       it != vertex_queue.end();
-       ++it) {
-    const Vertex vertex = *it;
+  for (const Vertex& vertex : vertex_queue) {
     DCHECK(vertex_color[vertex] != kWhite);
     if (vertex_color[vertex] != kBlack) {
       ordering->push_back(vertex);
@@ -173,7 +166,7 @@
 int StableIndependentSetOrdering(const Graph<Vertex>& graph,
                                  std::vector<Vertex>* ordering) {
   CHECK_NOTNULL(ordering);
-  const HashSet<Vertex>& vertices = graph.vertices();
+  const std::unordered_set<Vertex>& vertices = graph.vertices();
   const int num_vertices = vertices.size();
   CHECK_EQ(vertices.size(), ordering->size());
 
@@ -188,11 +181,9 @@
                   VertexDegreeLessThan<Vertex>(graph));
 
   // Mark all vertices white.
-  HashMap<Vertex, char> vertex_color;
-  for (typename HashSet<Vertex>::const_iterator it = vertices.begin();
-       it != vertices.end();
-       ++it) {
-    vertex_color[*it] = kWhite;
+  std::unordered_map<Vertex, char> vertex_color;
+  for (const Vertex& vertex : vertices) {
+    vertex_color[vertex] = kWhite;
   }
 
   ordering->clear();
@@ -207,11 +198,9 @@
 
     ordering->push_back(vertex);
     vertex_color[vertex] = kBlack;
-    const HashSet<Vertex>& neighbors = graph.Neighbors(vertex);
-    for (typename HashSet<Vertex>::const_iterator it = neighbors.begin();
-         it != neighbors.end();
-         ++it) {
-      vertex_color[*it] = kGrey;
+    const std::unordered_set<Vertex>& neighbors = graph.Neighbors(vertex);
+    for (const Vertex& neighbor : neighbors) {
+      vertex_color[neighbor] = kGrey;
     }
   }
 
@@ -220,10 +209,7 @@
   // Iterate over the vertices and add all the grey vertices to the
   // ordering. At this stage there should only be black or grey
   // vertices in the graph.
-  for (typename std::vector<Vertex>::const_iterator it = vertex_queue.begin();
-       it != vertex_queue.end();
-       ++it) {
-    const Vertex vertex = *it;
+  for (const Vertex& vertex : vertex_queue) {
     DCHECK(vertex_color[vertex] != kWhite);
     if (vertex_color[vertex] != kBlack) {
       ordering->push_back(vertex);
@@ -242,8 +228,8 @@
 // is what gives this data structure its efficiency.
 template <typename Vertex>
 Vertex FindConnectedComponent(const Vertex& vertex,
-                              HashMap<Vertex, Vertex>* union_find) {
-  typename HashMap<Vertex, Vertex>::iterator it = union_find->find(vertex);
+                              std::unordered_map<Vertex, Vertex>* union_find) {
+  auto it = union_find->find(vertex);
   DCHECK(it != union_find->end());
   if (it->second != vertex) {
     it->second = FindConnectedComponent(it->second, union_find);
@@ -279,25 +265,19 @@
 
   // Disjoint-set to keep track of the connected components in the
   // maximum spanning tree.
-  HashMap<Vertex, Vertex> disjoint_set;
+  std::unordered_map<Vertex, Vertex> disjoint_set;
 
   // Sort of the edges in the graph in decreasing order of their
   // weight. Also add the vertices of the graph to the Maximum
   // Spanning Tree graph and set each vertex to be its own connected
   // component in the disjoint_set structure.
-  const HashSet<Vertex>& vertices = graph.vertices();
-  for (typename HashSet<Vertex>::const_iterator it = vertices.begin();
-       it != vertices.end();
-       ++it) {
-    const Vertex vertex1 = *it;
+  const std::unordered_set<Vertex>& vertices = graph.vertices();
+  for (const Vertex& vertex1 : vertices) {
     forest->AddVertex(vertex1, graph.VertexWeight(vertex1));
     disjoint_set[vertex1] = vertex1;
 
-    const HashSet<Vertex>& neighbors = graph.Neighbors(vertex1);
-    for (typename HashSet<Vertex>::const_iterator it2 = neighbors.begin();
-         it2 != neighbors.end();
-         ++it2) {
-      const Vertex vertex2 = *it2;
+    const std::unordered_set<Vertex>& neighbors = graph.Neighbors(vertex1);
+    for (const Vertex& vertex2 : neighbors) {
       if (vertex1 >= vertex2) {
         continue;
       }
diff --git a/internal/ceres/graph_algorithms_test.cc b/internal/ceres/graph_algorithms_test.cc
index 1071488..160ece1 100644
--- a/internal/ceres/graph_algorithms_test.cc
+++ b/internal/ceres/graph_algorithms_test.cc
@@ -31,8 +31,8 @@
 #include "ceres/graph_algorithms.h"
 
 #include <algorithm>
+#include <unordered_set>
 #include "gtest/gtest.h"
-#include "ceres/collections_port.h"
 #include "ceres/graph.h"
 #include "ceres/internal/port.h"
 #include "ceres/internal/scoped_ptr.h"
@@ -112,7 +112,7 @@
 
   scoped_ptr<WeightedGraph<int> > forest(Degree2MaximumSpanningForest(graph));
 
-  const HashSet<int>& vertices = forest->vertices();
+  const std::unordered_set<int>& vertices = forest->vertices();
   EXPECT_EQ(vertices.size(), 2);
   EXPECT_EQ(forest->VertexWeight(0), 1.0);
   EXPECT_EQ(forest->VertexWeight(1), 2.0);
@@ -134,35 +134,35 @@
   graph.AddEdge(0, 4, 4.0);
 
   scoped_ptr<WeightedGraph<int> > forest(Degree2MaximumSpanningForest(graph));
-  const HashSet<int>& vertices = forest->vertices();
+  const std::unordered_set<int>& vertices = forest->vertices();
   EXPECT_EQ(vertices.size(), 5);
 
   {
-    const HashSet<int>& neighbors = forest->Neighbors(0);
+    const std::unordered_set<int>& neighbors = forest->Neighbors(0);
     EXPECT_EQ(neighbors.size(), 2);
     EXPECT_TRUE(neighbors.find(4) != neighbors.end());
     EXPECT_TRUE(neighbors.find(3) != neighbors.end());
   }
 
   {
-    const HashSet<int>& neighbors = forest->Neighbors(3);
+    const std::unordered_set<int>& neighbors = forest->Neighbors(3);
     EXPECT_EQ(neighbors.size(), 1);
     EXPECT_TRUE(neighbors.find(0) != neighbors.end());
   }
 
   {
-    const HashSet<int>& neighbors = forest->Neighbors(4);
+    const std::unordered_set<int>& neighbors = forest->Neighbors(4);
     EXPECT_EQ(neighbors.size(), 1);
     EXPECT_TRUE(neighbors.find(0) != neighbors.end());
   }
 
   {
-    const HashSet<int>& neighbors = forest->Neighbors(1);
+    const std::unordered_set<int>& neighbors = forest->Neighbors(1);
     EXPECT_EQ(neighbors.size(), 0);
   }
 
   {
-    const HashSet<int>& neighbors = forest->Neighbors(2);
+    const std::unordered_set<int>& neighbors = forest->Neighbors(2);
     EXPECT_EQ(neighbors.size(), 0);
   }
 }
diff --git a/internal/ceres/graph_test.cc b/internal/ceres/graph_test.cc
index e9d4e1c..0907f86 100644
--- a/internal/ceres/graph_test.cc
+++ b/internal/ceres/graph_test.cc
@@ -30,8 +30,8 @@
 
 #include "ceres/graph.h"
 
+#include <unordered_set>
 #include "gtest/gtest.h"
-#include "ceres/collections_port.h"
 #include "ceres/internal/scoped_ptr.h"
 
 namespace ceres {
@@ -48,7 +48,7 @@
   graph.AddVertex(1);
   graph.AddEdge(0, 1);
 
-  const HashSet<int>& vertices = graph.vertices();
+  const std::unordered_set<int>& vertices = graph.vertices();
   EXPECT_EQ(vertices.size(), 2);
   EXPECT_EQ(graph.Neighbors(0).size(), 1);
   EXPECT_EQ(graph.Neighbors(1).size(), 1);
@@ -60,7 +60,7 @@
   graph.AddVertex(1);
   graph.AddEdge(0, 1);
 
-  const HashSet<int>& vertices = graph.vertices();
+  const std::unordered_set<int>& vertices = graph.vertices();
 
   EXPECT_EQ(vertices.size(), 2);
 
@@ -93,7 +93,7 @@
   graph.AddVertex(1, 2.0);
   graph.AddEdge(0, 1, 0.5);
 
-  const HashSet<int>& vertices = graph.vertices();
+  const std::unordered_set<int>& vertices = graph.vertices();
   EXPECT_EQ(vertices.size(), 2);
   EXPECT_EQ(graph.VertexWeight(0), 1.0);
   EXPECT_EQ(graph.VertexWeight(1), 2.0);
@@ -109,7 +109,7 @@
   graph.AddVertex(1, 2.0);
   graph.AddEdge(0, 1, 0.5);
 
-  const HashSet<int>& vertices = graph.vertices();
+  const std::unordered_set<int>& vertices = graph.vertices();
 
   EXPECT_EQ(vertices.size(), 2);
 
diff --git a/internal/ceres/low_rank_inverse_hessian.cc b/internal/ceres/low_rank_inverse_hessian.cc
index 1c6c992..f3953c4 100644
--- a/internal/ceres/low_rank_inverse_hessian.cc
+++ b/internal/ceres/low_rank_inverse_hessian.cc
@@ -175,12 +175,10 @@
             << "approximation.";
   }
 
-  for (list<int>::const_iterator it = indices_.begin();
-       it != indices_.end();
-       ++it) {
-    const double beta = delta_gradient_history_.col(*it).dot(search_direction) /
-        delta_x_dot_delta_gradient_(*it);
-    search_direction += delta_x_history_.col(*it) * (alpha(*it) - beta);
+  for (const int i : indices_) {
+    const double beta = delta_gradient_history_.col(i).dot(search_direction) /
+        delta_x_dot_delta_gradient_(i);
+    search_direction += delta_x_history_.col(i) * (alpha(i) - beta);
   }
 }
 
diff --git a/internal/ceres/ordered_groups_test.cc b/internal/ceres/ordered_groups_test.cc
index 4510686..8cf4324 100644
--- a/internal/ceres/ordered_groups_test.cc
+++ b/internal/ceres/ordered_groups_test.cc
@@ -33,7 +33,6 @@
 #include <cstddef>
 #include <vector>
 #include "gtest/gtest.h"
-#include "ceres/collections_port.h"
 
 namespace ceres {
 namespace internal {
diff --git a/internal/ceres/pair_hash.h b/internal/ceres/pair_hash.h
new file mode 100644
index 0000000..7fb32cf
--- /dev/null
+++ b/internal/ceres/pair_hash.h
@@ -0,0 +1,112 @@
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2018 Google Inc. All rights reserved.
+// http://ceres-solver.org/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+//   used to endorse or promote products derived from this software without
+//   specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: keir@google.com (Keir Mierle)
+//
+// A hasher for std::pair<T, T>.
+
+#ifndef CERES_INTERNAL_PAIR_HASH_H_
+#define CERES_INTERNAL_PAIR_HASH_H_
+
+#include "ceres/internal/port.h"
+#include <utility>
+#include "ceres/integral_types.h"
+
+namespace ceres {
+namespace internal {
+
+#if defined(_WIN32) && !defined(__MINGW64__) && !defined(__MINGW32__)
+#define GG_LONGLONG(x) x##I64
+#define GG_ULONGLONG(x) x##UI64
+#else
+#define GG_LONGLONG(x) x##LL
+#define GG_ULONGLONG(x) x##ULL
+#endif
+
+// The hash function is due to Bob Jenkins (see
+// http://burtleburtle.net/bob/hash/index.html). Each mix takes 36 instructions,
+// in 18 cycles if you're lucky. On x86 architectures, this requires 45
+// instructions in 27 cycles, if you're lucky.
+//
+// 32bit version
+inline void hash_mix(uint32& a, uint32& b, uint32& c) {
+  a -= b; a -= c; a ^= (c>>13);
+  b -= c; b -= a; b ^= (a<<8);
+  c -= a; c -= b; c ^= (b>>13);
+  a -= b; a -= c; a ^= (c>>12);
+  b -= c; b -= a; b ^= (a<<16);
+  c -= a; c -= b; c ^= (b>>5);
+  a -= b; a -= c; a ^= (c>>3);
+  b -= c; b -= a; b ^= (a<<10);
+  c -= a; c -= b; c ^= (b>>15);
+}
+
+// 64bit version
+inline void hash_mix(uint64& a, uint64& b, uint64& c) {
+  a -= b; a -= c; a ^= (c>>43);
+  b -= c; b -= a; b ^= (a<<9);
+  c -= a; c -= b; c ^= (b>>8);
+  a -= b; a -= c; a ^= (c>>38);
+  b -= c; b -= a; b ^= (a<<23);
+  c -= a; c -= b; c ^= (b>>5);
+  a -= b; a -= c; a ^= (c>>35);
+  b -= c; b -= a; b ^= (a<<49);
+  c -= a; c -= b; c ^= (b>>11);
+}
+
+inline uint32 Hash32NumWithSeed(uint32 num, uint32 c) {
+  // The golden ratio; an arbitrary value.
+  uint32 b = 0x9e3779b9UL;
+  hash_mix(num, b, c);
+  return c;
+}
+
+inline uint64 Hash64NumWithSeed(uint64 num, uint64 c) {
+  // More of the golden ratio.
+  uint64 b = GG_ULONGLONG(0xe08c1d668b756f82);
+  hash_mix(num, b, c);
+  return c;
+}
+
+// Hasher for STL pairs. Requires hashers for both members to be defined.
+struct pair_hash {
+ public:
+  template <typename T>
+  std::size_t operator()(const std::pair<T, T>& p) const {
+    const std::size_t h1 = std::hash<T>()(p.first);
+    const std::size_t h2 = std::hash<T>()(p.second);
+    // The decision below is at compile time
+    return (sizeof(h1) <= sizeof(uint32)) ? Hash32NumWithSeed(h1, h2)
+                                          : Hash64NumWithSeed(h1, h2);
+  }
+};
+
+}  // namespace internal
+}  // namespace ceres
+
+#endif  // CERES_INTERNAL_PAIR_HASH_H_
diff --git a/internal/ceres/parameter_block.h b/internal/ceres/parameter_block.h
index 8e21553..a41d9d1 100644
--- a/internal/ceres/parameter_block.h
+++ b/internal/ceres/parameter_block.h
@@ -35,8 +35,8 @@
 #include <cstdlib>
 #include <limits>
 #include <string>
+#include <unordered_set>
 #include "ceres/array_utils.h"
-#include "ceres/collections_port.h"
 #include "ceres/integral_types.h"
 #include "ceres/internal/eigen.h"
 #include "ceres/internal/port.h"
@@ -71,7 +71,7 @@
   // when it is small, but transitions to a hash set when it has more elements.
   //
   // For now, use a hash set.
-  typedef HashSet<ResidualBlock*> ResidualBlockSet;
+  typedef std::unordered_set<ResidualBlock*> ResidualBlockSet;
 
   // Create a parameter block with the user state, size, and index specified.
   // The size is the size of the parameter block and the index is the position
diff --git a/internal/ceres/parameter_block_ordering.cc b/internal/ceres/parameter_block_ordering.cc
index efba339..649ce14 100644
--- a/internal/ceres/parameter_block_ordering.cc
+++ b/internal/ceres/parameter_block_ordering.cc
@@ -30,6 +30,7 @@
 
 #include "ceres/parameter_block_ordering.h"
 
+#include <unordered_set>
 #include "ceres/graph.h"
 #include "ceres/graph_algorithms.h"
 #include "ceres/internal/scoped_ptr.h"
@@ -55,7 +56,7 @@
   event_logger.AddEvent("CreateHessianGraph");
 
   const vector<ParameterBlock*>& parameter_blocks = program.parameter_blocks();
-  const HashSet<ParameterBlock*>& vertices = graph->vertices();
+  const std::unordered_set<ParameterBlock*>& vertices = graph->vertices();
   for (int i = 0; i < parameter_blocks.size(); ++i) {
     if (vertices.count(parameter_blocks[i]) > 0) {
       ordering->push_back(parameter_blocks[i]);
@@ -162,10 +163,8 @@
 
   const map<int, set<double*> >& group_to_elements =
       ordering->group_to_elements();
-  for (map<int, set<double*> >::const_iterator it = group_to_elements.begin();
-       it != group_to_elements.end();
-       ++it) {
-    group_sizes->push_back(it->second.size());
+  for (const auto& g_t_e : group_to_elements) {
+    group_sizes->push_back(g_t_e.second.size());
   }
 }
 
diff --git a/internal/ceres/parameter_block_ordering_test.cc b/internal/ceres/parameter_block_ordering_test.cc
index c98cdb5..41babff 100644
--- a/internal/ceres/parameter_block_ordering_test.cc
+++ b/internal/ceres/parameter_block_ordering_test.cc
@@ -31,9 +31,9 @@
 #include "ceres/parameter_block_ordering.h"
 
 #include <cstddef>
+#include <unordered_set>
 #include <vector>
 #include "gtest/gtest.h"
-#include "ceres/collections_port.h"
 #include "ceres/graph.h"
 #include "ceres/problem_impl.h"
 #include "ceres/program.h"
@@ -48,7 +48,7 @@
 using std::vector;
 
 typedef Graph<ParameterBlock*> HessianGraph;
-typedef HashSet<ParameterBlock*> VertexSet;
+typedef std::unordered_set<ParameterBlock*> VertexSet;
 
 template <int M, int N1 = 0, int N2 = 0, int N3 = 0>
 class DummyCostFunction: public SizedCostFunction<M, N1, N2, N3> {
diff --git a/internal/ceres/problem_impl.cc b/internal/ceres/problem_impl.cc
index 3ed0efd..1f3c55b 100644
--- a/internal/ceres/problem_impl.cc
+++ b/internal/ceres/problem_impl.cc
@@ -63,7 +63,6 @@
 using std::map;
 using std::string;
 using std::vector;
-typedef std::map<double*, internal::ParameterBlock*> ParameterMap;
 
 namespace {
 // Returns true if two regions of memory, a and b, with sizes size_a and size_b
@@ -90,7 +89,7 @@
 template <typename KeyType>
 void DecrementValueOrDeleteKey(const KeyType key,
                                std::map<KeyType, int>* container) {
-  typename std::map<KeyType, int>::iterator it = container->find(key);
+  auto it = container->find(key);
   if (it->second == 1) {
     delete key;
     container->erase(it);
@@ -936,10 +935,9 @@
 void ProblemImpl::GetParameterBlocks(vector<double*>* parameter_blocks) const {
   CHECK_NOTNULL(parameter_blocks);
   parameter_blocks->resize(0);
-  for (ParameterMap::const_iterator it = parameter_block_map_.begin();
-       it != parameter_block_map_.end();
-       ++it) {
-    parameter_blocks->push_back(it->first);
+  parameter_blocks->reserve(parameter_block_map_.size());
+  for (const auto& entry : parameter_block_map_) {
+    parameter_blocks->push_back(entry.first);
   }
 }
 
diff --git a/internal/ceres/problem_impl.h b/internal/ceres/problem_impl.h
index 03e61d2..4c24e3b 100644
--- a/internal/ceres/problem_impl.h
+++ b/internal/ceres/problem_impl.h
@@ -40,9 +40,9 @@
 #define CERES_PUBLIC_PROBLEM_IMPL_H_
 
 #include <map>
+#include <unordered_set>
 #include <vector>
 
-#include "ceres/collections_port.h"
 #include "ceres/context_impl.h"
 #include "ceres/internal/macros.h"
 #include "ceres/internal/port.h"
@@ -65,7 +65,7 @@
 class ProblemImpl {
  public:
   typedef std::map<double*, ParameterBlock*> ParameterMap;
-  typedef HashSet<ResidualBlock*> ResidualBlockSet;
+  typedef std::unordered_set<ResidualBlock*> ResidualBlockSet;
   typedef std::map<CostFunction*, int> CostFunctionRefCount;
   typedef std::map<LossFunction*, int> LossFunctionRefCount;
 
@@ -203,7 +203,7 @@
   ContextImpl* context_impl_;
 
   // The mapping from user pointers to parameter blocks.
-  std::map<double*, ParameterBlock*> parameter_block_map_;
+  ParameterMap parameter_block_map_;
 
   // Iff enable_fast_removal is enabled, contains the current residual blocks.
   ResidualBlockSet residual_block_set_;
diff --git a/internal/ceres/program.cc b/internal/ceres/program.cc
index 8e97f07..f6cd138 100644
--- a/internal/ceres/program.cc
+++ b/internal/ceres/program.cc
@@ -373,11 +373,10 @@
   // blocks in the same residual block are part of
   // parameter_block_ptrs as that would violate the assumption that it
   // is an independent set in the Hessian matrix.
-  for (vector<ResidualBlock*>::const_iterator it = residual_blocks_.begin();
-       it != residual_blocks_.end();
-       ++it) {
-    ParameterBlock* const* parameter_blocks = (*it)->parameter_blocks();
-    const int num_parameter_blocks = (*it)->NumParameterBlocks();
+  for (const ResidualBlock* residual_block : residual_blocks_) {
+    ParameterBlock* const* parameter_blocks =
+        residual_block->parameter_blocks();
+    const int num_parameter_blocks = residual_block->NumParameterBlocks();
     int count = 0;
     for (int i = 0; i < num_parameter_blocks; ++i) {
       count += independent_set.count(
diff --git a/internal/ceres/reorder_program.cc b/internal/ceres/reorder_program.cc
index a7c3710..94a35bd 100644
--- a/internal/ceres/reorder_program.cc
+++ b/internal/ceres/reorder_program.cc
@@ -234,23 +234,18 @@
   parameter_blocks->clear();
 
   const map<int, set<double*> >& groups = ordering.group_to_elements();
-  for (map<int, set<double*> >::const_iterator group_it = groups.begin();
-       group_it != groups.end();
-       ++group_it) {
-    const set<double*>& group = group_it->second;
-    for (set<double*>::const_iterator parameter_block_ptr_it = group.begin();
-         parameter_block_ptr_it != group.end();
-         ++parameter_block_ptr_it) {
-      ProblemImpl::ParameterMap::const_iterator parameter_block_it =
-          parameter_map.find(*parameter_block_ptr_it);
-      if (parameter_block_it == parameter_map.end()) {
+  for (const auto& p : groups) {
+    const set<double*>& group = p.second;
+    for (double* parameter_block_ptr : group) {
+      auto it = parameter_map.find(parameter_block_ptr);
+      if (it == parameter_map.end()) {
         *error = StringPrintf("User specified ordering contains a pointer "
                               "to a double that is not a parameter block in "
                               "the problem. The invalid double is in group: %d",
-                              group_it->first);
+                              p.first);
         return false;
       }
-      parameter_blocks->push_back(parameter_block_it->second);
+      parameter_blocks->push_back(it->second);
     }
   }
   return true;
diff --git a/internal/ceres/schur_jacobi_preconditioner.cc b/internal/ceres/schur_jacobi_preconditioner.cc
index d7f6fe9..13e6463 100644
--- a/internal/ceres/schur_jacobi_preconditioner.cc
+++ b/internal/ceres/schur_jacobi_preconditioner.cc
@@ -34,7 +34,6 @@
 #include <vector>
 #include "ceres/block_random_access_diagonal_matrix.h"
 #include "ceres/block_sparse_matrix.h"
-#include "ceres/collections_port.h"
 #include "ceres/internal/scoped_ptr.h"
 #include "ceres/linear_solver.h"
 #include "ceres/schur_eliminator.h"
diff --git a/internal/ceres/schur_jacobi_preconditioner.h b/internal/ceres/schur_jacobi_preconditioner.h
index 5398f3f..fb7753b 100644
--- a/internal/ceres/schur_jacobi_preconditioner.h
+++ b/internal/ceres/schur_jacobi_preconditioner.h
@@ -41,7 +41,6 @@
 #include <set>
 #include <vector>
 #include <utility>
-#include "ceres/collections_port.h"
 #include "ceres/internal/macros.h"
 #include "ceres/internal/scoped_ptr.h"
 #include "ceres/preconditioner.h"
diff --git a/internal/ceres/single_linkage_clustering.cc b/internal/ceres/single_linkage_clustering.cc
index 9e9342a..2d3213a 100644
--- a/internal/ceres/single_linkage_clustering.cc
+++ b/internal/ceres/single_linkage_clustering.cc
@@ -30,8 +30,9 @@
 
 #include "ceres/single_linkage_clustering.h"
 
+#include <unordered_set>
+#include <unordered_map>
 #include "ceres/graph.h"
-#include "ceres/collections_port.h"
 #include "ceres/graph_algorithms.h"
 
 namespace ceres {
@@ -40,27 +41,18 @@
 int ComputeSingleLinkageClustering(
     const SingleLinkageClusteringOptions& options,
     const WeightedGraph<int>& graph,
-    HashMap<int, int>* membership) {
+    std::unordered_map<int, int>* membership) {
   CHECK_NOTNULL(membership)->clear();
 
   // Initially each vertex is in its own cluster.
-  const HashSet<int>& vertices = graph.vertices();
-  for (HashSet<int>::const_iterator it = vertices.begin();
-       it != vertices.end();
-       ++it) {
-    (*membership)[*it] = *it;
+  const std::unordered_set<int>& vertices = graph.vertices();
+  for (const int v : vertices) {
+    (*membership)[v] = v;
   }
 
-  for (HashSet<int>::const_iterator it1 = vertices.begin();
-       it1 != vertices.end();
-       ++it1) {
-    const int vertex1 = *it1;
-    const HashSet<int>& neighbors = graph.Neighbors(vertex1);
-    for (HashSet<int>::const_iterator it2 = neighbors.begin();
-         it2 != neighbors.end();
-         ++it2) {
-      const int vertex2 = *it2;
-
+  for (const int vertex1 : vertices) {
+    const std::unordered_set<int>& neighbors = graph.Neighbors(vertex1);
+    for (const int vertex2 : neighbors) {
       // Since the graph is undirected, only pay attention to one side
       // of the edge and ignore weak edges.
       if ((vertex1 > vertex2) ||
@@ -87,11 +79,9 @@
   // Make sure that every vertex is connected directly to the vertex
   // identifying the cluster.
   int num_clusters = 0;
-  for (HashMap<int, int>::iterator it = membership->begin();
-       it != membership->end();
-       ++it) {
-    it->second = FindConnectedComponent(it->first, membership);
-    if (it->first == it->second) {
+  for (auto& m : *membership) {
+    m.second = FindConnectedComponent(m.first, membership);
+    if (m.first == m.second) {
       ++num_clusters;
     }
   }
diff --git a/internal/ceres/single_linkage_clustering.h b/internal/ceres/single_linkage_clustering.h
index 8d1f02b..374125b 100644
--- a/internal/ceres/single_linkage_clustering.h
+++ b/internal/ceres/single_linkage_clustering.h
@@ -31,7 +31,7 @@
 #ifndef CERES_INTERNAL_SINGLE_LINKAGE_CLUSTERING_H_
 #define CERES_INTERNAL_SINGLE_LINKAGE_CLUSTERING_H_
 
-#include "ceres/collections_port.h"
+#include <unordered_map>
 #include "ceres/graph.h"
 
 namespace ceres {
@@ -60,7 +60,7 @@
 int ComputeSingleLinkageClustering(
     const SingleLinkageClusteringOptions& options,
     const WeightedGraph<int>& graph,
-    HashMap<int, int>* membership);
+    std::unordered_map<int, int>* membership);
 
 }  // namespace internal
 }  // namespace ceres
diff --git a/internal/ceres/single_linkage_clustering_test.cc b/internal/ceres/single_linkage_clustering_test.cc
index ca1a661..281c281 100644
--- a/internal/ceres/single_linkage_clustering_test.cc
+++ b/internal/ceres/single_linkage_clustering_test.cc
@@ -30,7 +30,7 @@
 
 #include "ceres/single_linkage_clustering.h"
 
-#include "ceres/collections_port.h"
+#include <unordered_map>
 #include "ceres/graph.h"
 #include "gtest/gtest.h"
 
@@ -52,7 +52,7 @@
   graph.AddEdge(4, 5, 1.0);
 
   SingleLinkageClusteringOptions options;
-  HashMap<int, int> membership;
+  std::unordered_map<int, int> membership;
   ComputeSingleLinkageClustering(options, graph, &membership);
   EXPECT_EQ(membership.size(), kNumVertices);
 
@@ -81,7 +81,7 @@
   graph.AddEdge(4, 5, 0.5);
 
   SingleLinkageClusteringOptions options;
-  HashMap<int, int> membership;
+  std::unordered_map<int, int> membership;
   ComputeSingleLinkageClustering(options, graph, &membership);
   EXPECT_EQ(membership.size(), kNumVertices);
 
@@ -111,7 +111,7 @@
   graph.AddEdge(4, 5, 1.0);
 
   SingleLinkageClusteringOptions options;
-  HashMap<int, int> membership;
+  std::unordered_map<int, int> membership;
   ComputeSingleLinkageClustering(options, graph, &membership);
   EXPECT_EQ(membership.size(), kNumVertices);
 
diff --git a/internal/ceres/visibility.cc b/internal/ceres/visibility.cc
index cb962a6..a446b6b 100644
--- a/internal/ceres/visibility.cc
+++ b/internal/ceres/visibility.cc
@@ -35,10 +35,11 @@
 #include <algorithm>
 #include <set>
 #include <vector>
+#include <unordered_map>
 #include <utility>
 #include "ceres/block_structure.h"
-#include "ceres/collections_port.h"
 #include "ceres/graph.h"
+#include "ceres/pair_hash.h"
 #include "glog/logging.h"
 
 namespace ceres {
@@ -98,22 +99,17 @@
   vector<set<int> > inverse_visibility(num_points);
   for (int i = 0; i < visibility.size(); i++) {
     const set<int>& visibility_set = visibility[i];
-    for (set<int>::const_iterator it = visibility_set.begin();
-         it != visibility_set.end();
-         ++it) {
-      inverse_visibility[*it].insert(i);
+    for (const int v : visibility_set) {
+      inverse_visibility[v].insert(i);
     }
   }
 
   // Map from camera pairs to number of points visible to both cameras
   // in the pair.
-  HashMap<pair<int, int>, int > camera_pairs;
+  std::unordered_map<pair<int, int>, int, pair_hash> camera_pairs;
 
   // Count the number of points visible to each camera/f_block pair.
-  for (vector<set<int> >::const_iterator it = inverse_visibility.begin();
-       it != inverse_visibility.end();
-       ++it) {
-    const set<int>& inverse_visibility_set = *it;
+  for (const auto& inverse_visibility_set : inverse_visibility) {
     for (set<int>::const_iterator camera1 = inverse_visibility_set.begin();
          camera1 != inverse_visibility_set.end();
          ++camera1) {
@@ -136,14 +132,11 @@
   }
 
   // Add an edge for each camera pair.
-  for (HashMap<pair<int, int>, int>::const_iterator it = camera_pairs.begin();
-       it != camera_pairs.end();
-       ++it) {
-    const int camera1 = it->first.first;
-    const int camera2 = it->first.second;
-    CHECK_NE(camera1, camera2);
-
-    const int count = it->second;
+  for (const auto& camera_pair_count : camera_pairs) {
+    const int camera1 = camera_pair_count.first.first;
+    const int camera2 = camera_pair_count.first.second;
+    const int count = camera_pair_count.second;
+    DCHECK_NE(camera1, camera2);
     // Static cast necessary for Windows.
     const double weight = static_cast<double>(count) /
         (sqrt(static_cast<double>(
diff --git a/internal/ceres/visibility_based_preconditioner.cc b/internal/ceres/visibility_based_preconditioner.cc
index 24563ae..31d2cc3 100644
--- a/internal/ceres/visibility_based_preconditioner.cc
+++ b/internal/ceres/visibility_based_preconditioner.cc
@@ -40,7 +40,6 @@
 #include "ceres/block_random_access_sparse_matrix.h"
 #include "ceres/block_sparse_matrix.h"
 #include "ceres/canonical_views_clustering.h"
-#include "ceres/collections_port.h"
 #include "ceres/graph.h"
 #include "ceres/graph_algorithms.h"
 #include "ceres/internal/scoped_ptr.h"
@@ -177,7 +176,7 @@
   scoped_ptr<WeightedGraph<int> > schur_complement_graph(
       CHECK_NOTNULL(CreateSchurComplementGraph(visibility)));
 
-  HashMap<int, int> membership;
+  std::unordered_map<int, int> membership;
 
   if (options_.visibility_clustering_type == CANONICAL_VIEWS) {
     vector<int> centers;
@@ -382,11 +381,9 @@
 // matrix. Scaling these off-diagonal entries by 1/2 forces this
 // matrix to be positive definite.
 void VisibilityBasedPreconditioner::ScaleOffDiagonalCells() {
-  for (set<pair<int, int> >::const_iterator it = block_pairs_.begin();
-       it != block_pairs_.end();
-       ++it) {
-    const int block1 = it->first;
-    const int block2 = it->second;
+  for (const auto& block_pair : block_pairs_) {
+    const int block1 = block_pair.first;
+    const int block2 = block_pair.second;
     if (!IsBlockPairOffDiagonal(block1, block2)) {
       continue;
     }
@@ -464,23 +461,17 @@
 // each vertex.
 void VisibilityBasedPreconditioner::ForestToClusterPairs(
     const WeightedGraph<int>& forest,
-    HashSet<pair<int, int> >* cluster_pairs) const {
+    std::unordered_set<pair<int, int>, pair_hash >* cluster_pairs) const {
   CHECK_NOTNULL(cluster_pairs)->clear();
-  const HashSet<int>& vertices = forest.vertices();
+  const std::unordered_set<int>& vertices = forest.vertices();
   CHECK_EQ(vertices.size(), num_clusters_);
 
   // Add all the cluster pairs corresponding to the edges in the
   // forest.
-  for (HashSet<int>::const_iterator it1 = vertices.begin();
-       it1 != vertices.end();
-       ++it1) {
-    const int cluster1 = *it1;
+  for (const int cluster1 : vertices) {
     cluster_pairs->insert(make_pair(cluster1, cluster1));
-    const HashSet<int>& neighbors = forest.Neighbors(cluster1);
-    for (HashSet<int>::const_iterator it2 = neighbors.begin();
-         it2 != neighbors.end();
-         ++it2) {
-      const int cluster2 = *it2;
+    const std::unordered_set<int>& neighbors = forest.Neighbors(cluster1);
+    for (const int cluster2 : neighbors) {
       if (cluster1 < cluster2) {
         cluster_pairs->insert(make_pair(cluster1, cluster2));
       }
@@ -538,7 +529,7 @@
   return cluster_graph;
 }
 
-// Canonical views clustering returns a HashMap from vertices to
+// Canonical views clustering returns a std::unordered_map from vertices to
 // cluster ids. Convert this into a flat array for quick lookup. It is
 // possible that some of the vertices may not be associated with any
 // cluster. In that case, randomly assign them to one of the clusters.
@@ -547,20 +538,18 @@
 // the membership_map, we also map the cluster ids to a contiguous set
 // of integers so that the cluster ids are in [0, num_clusters_).
 void VisibilityBasedPreconditioner::FlattenMembershipMap(
-    const HashMap<int, int>& membership_map,
+    const std::unordered_map<int, int>& membership_map,
     vector<int>* membership_vector) const {
   CHECK_NOTNULL(membership_vector)->resize(0);
   membership_vector->resize(num_blocks_, -1);
 
-  HashMap<int, int> cluster_id_to_index;
+  std::unordered_map<int, int> cluster_id_to_index;
   // Iterate over the cluster membership map and update the
   // cluster_membership_ vector assigning arbitrary cluster ids to
   // the few cameras that have not been clustered.
-  for (HashMap<int, int>::const_iterator it = membership_map.begin();
-       it != membership_map.end();
-       ++it) {
-    const int camera_id = it->first;
-    int cluster_id = it->second;
+  for (const auto& m : membership_map) {
+    const int camera_id = m.first;
+    int cluster_id = m.second;
 
     // If the view was not clustered, randomly assign it to one of the
     // clusters. This preserves the mathematical correctness of the
diff --git a/internal/ceres/visibility_based_preconditioner.h b/internal/ceres/visibility_based_preconditioner.h
index 40ce2c7..1c831d0 100644
--- a/internal/ceres/visibility_based_preconditioner.h
+++ b/internal/ceres/visibility_based_preconditioner.h
@@ -49,13 +49,15 @@
 #define CERES_INTERNAL_VISIBILITY_BASED_PRECONDITIONER_H_
 
 #include <set>
+#include <unordered_map>
+#include <unordered_set>
 #include <utility>
 #include <vector>
-#include "ceres/collections_port.h"
 #include "ceres/graph.h"
 #include "ceres/internal/macros.h"
 #include "ceres/internal/scoped_ptr.h"
 #include "ceres/linear_solver.h"
+#include "ceres/pair_hash.h"
 #include "ceres/preconditioner.h"
 #include "ceres/sparse_cholesky.h"
 
@@ -150,7 +152,7 @@
   void ScaleOffDiagonalCells();
 
   void ClusterCameras(const std::vector<std::set<int> >& visibility);
-  void FlattenMembershipMap(const HashMap<int, int>& membership_map,
+  void FlattenMembershipMap(const std::unordered_map<int, int>& membership_map,
                             std::vector<int>* membership_vector) const;
   void ComputeClusterVisibility(
       const std::vector<std::set<int> >& visibility,
@@ -158,7 +160,7 @@
   WeightedGraph<int>* CreateClusterGraph(
       const std::vector<std::set<int> >& visibility) const;
   void ForestToClusterPairs(const WeightedGraph<int>& forest,
-                            HashSet<std::pair<int, int> >* cluster_pairs) const;
+                            std::unordered_set<std::pair<int, int>, pair_hash>* cluster_pairs) const;
   void ComputeBlockPairsInPreconditioner(const CompressedRowBlockStructure& bs);
   bool IsBlockPairInPreconditioner(int block1, int block2) const;
   bool IsBlockPairOffDiagonal(int block1, int block2) const;
@@ -182,7 +184,7 @@
 
   // Set of cluster pairs (including self pairs (i,i)) in the
   // preconditioner.
-  HashSet<std::pair<int, int> > cluster_pairs_;
+  std::unordered_set<std::pair<int, int>, pair_hash> cluster_pairs_;
   scoped_ptr<SchurEliminatorBase> eliminator_;
 
   // Preconditioner matrix.
diff --git a/internal/ceres/visibility_based_preconditioner_test.cc b/internal/ceres/visibility_based_preconditioner_test.cc
index d2f13bc..2227116 100644
--- a/internal/ceres/visibility_based_preconditioner_test.cc
+++ b/internal/ceres/visibility_based_preconditioner_test.cc
@@ -35,15 +35,14 @@
 #include "ceres/block_random_access_sparse_matrix.h"
 #include "ceres/block_sparse_matrix.h"
 #include "ceres/casts.h"
-#include "ceres/collections_port.h"
 #include "ceres/file.h"
 #include "ceres/internal/eigen.h"
 #include "ceres/internal/scoped_ptr.h"
 #include "ceres/linear_least_squares_problems.h"
 #include "ceres/schur_eliminator.h"
 #include "ceres/stringprintf.h"
-#include "ceres/types.h"
 #include "ceres/test_util.h"
+#include "ceres/types.h"
 #include "glog/logging.h"
 #include "gtest/gtest.h"
 
@@ -110,11 +109,11 @@
 //                           schur_complement_.get(), rhs.data());
 //   }
 
-
 //   AssertionResult IsSparsityStructureValid() {
 //     preconditioner_->InitStorage(*A_->block_structure());
-//     const HashSet<pair<int, int> >& cluster_pairs = get_cluster_pairs();
-//     const vector<int>& cluster_membership = get_cluster_membership();
+//     const std::unordered_set<pair<int, int>, pair_hash>& cluster_pairs =
+//     get_cluster_pairs(); const vector<int>& cluster_membership =
+//     get_cluster_membership();
 
 //     for (int i = 0; i < num_camera_blocks_; ++i) {
 //       for (int j = i; j < num_camera_blocks_; ++j) {
@@ -137,8 +136,8 @@
 
 //   AssertionResult PreconditionerValuesMatch() {
 //     preconditioner_->Update(*A_, D_.get());
-//     const HashSet<pair<int, int> >& cluster_pairs = get_cluster_pairs();
-//     const BlockRandomAccessSparseMatrix* m = get_m();
+//     const std::unordered_set<pair<int, int>, pair_hash>& cluster_pairs =
+//     get_cluster_pairs(); const BlockRandomAccessSparseMatrix* m = get_m();
 //     Matrix preconditioner_matrix;
 //     m->matrix()->ToDenseMatrix(&preconditioner_matrix);
 //     ConstMatrixRef full_schur_complement(schur_complement_->values(),
@@ -205,11 +204,12 @@
 //     return &preconditioner_->block_pairs_;
 //   }
 
-//   const HashSet<pair<int, int> >& get_cluster_pairs() {
+//   const std::unordered_set<pair<int, int>, pair_hash>& get_cluster_pairs() {
 //     return preconditioner_->cluster_pairs_;
 //   }
 
-//   HashSet<pair<int, int> >* get_mutable_cluster_pairs() {
+//   std::unordered_set<pair<int, int>, pair_hash>* get_mutable_cluster_pairs()
+//   {
 //     return &preconditioner_->cluster_pairs_;
 //   }
 
@@ -253,8 +253,8 @@
 
 //   *get_mutable_num_clusters() = 1;
 
-//   HashSet<pair<int, int> >& cluster_pairs = *get_mutable_cluster_pairs();
-//   cluster_pairs.clear();
+//   std::unordered_set<pair<int, int>, pair_hash>& cluster_pairs =
+//   *get_mutable_cluster_pairs(); cluster_pairs.clear();
 //   cluster_pairs.insert(make_pair(0, 0));
 
 //   EXPECT_TRUE(IsSparsityStructureValid());
@@ -284,8 +284,6 @@
 //   }
 // }
 
-
-
 // TEST_F(VisibilityBasedPreconditionerTest, ClusterJacobi) {
 //   options_.type = CLUSTER_JACOBI;
 //   preconditioner_.reset(
@@ -301,9 +299,9 @@
 //   }
 //   *get_mutable_num_clusters() = kNumClusters;
 
-//   HashSet<pair<int, int> >& cluster_pairs = *get_mutable_cluster_pairs();
-//   cluster_pairs.clear();
-//   for (int i = 0; i < kNumClusters; ++i) {
+//   std::unordered_set<pair<int, int>, pair_hash>& cluster_pairs =
+//   *get_mutable_cluster_pairs(); cluster_pairs.clear(); for (int i = 0; i <
+//   kNumClusters; ++i) {
 //     cluster_pairs.insert(make_pair(i, i));
 //   }
 
@@ -311,7 +309,6 @@
 //   EXPECT_TRUE(PreconditionerValuesMatch());
 // }
 
-
 // TEST_F(VisibilityBasedPreconditionerTest, ClusterTridiagonal) {
 //   options_.type = CLUSTER_TRIDIAGONAL;
 //   preconditioner_.reset(
@@ -327,9 +324,9 @@
 //   *get_mutable_num_clusters() = kNumClusters;
 
 //   // Spanning forest has structure 0-1 2
-//   HashSet<pair<int, int> >& cluster_pairs = *get_mutable_cluster_pairs();
-//   cluster_pairs.clear();
-//   for (int i = 0; i < kNumClusters; ++i) {
+//   std::unordered_set<pair<int, int>, pair_hash>& cluster_pairs =
+//   *get_mutable_cluster_pairs(); cluster_pairs.clear(); for (int i = 0; i <
+//   kNumClusters; ++i) {
 //     cluster_pairs.insert(make_pair(i, i));
 //   }
 //   cluster_pairs.insert(make_pair(0, 1));