diff --git a/tensorflow/compiler/jit/extract_outside_compilation_pass.cc b/tensorflow/compiler/jit/extract_outside_compilation_pass.cc
index 9be72089dc3..5f1c3d536a8 100644
--- a/tensorflow/compiler/jit/extract_outside_compilation_pass.cc
+++ b/tensorflow/compiler/jit/extract_outside_compilation_pass.cc
@@ -321,7 +321,7 @@ xla::StatusOr<NodeDef> BuildXlaHostComputeNodeDef(
                             host_compute_builder.node_name());
 
   // Copy all attributes.
-  for (auto attr : call_node->attrs()) {
+  for (const auto& attr : call_node->attrs()) {
     host_compute_builder.Attr(attr.first, attr.second);
   }
 
@@ -346,7 +346,7 @@ xla::StatusOr<NodeDef> BuildXlaHostComputeNodeDef(
   xla_token_input_nodes.emplace_back(kXlaTokenArgNodeName);
   auto cluster_deps_it = cluster_deps.find(original_oc_name);
   if (cluster_deps_it != cluster_deps.end()) {
-    for (auto dep : cluster_deps_it->second) {
+    for (const auto& dep : cluster_deps_it->second) {
       xla_token_input_nodes.emplace_back(host_compute_node_name(dep));
     }
   }
@@ -2359,7 +2359,7 @@ Status ExtractOutsideCompilationForFunction(
     }
     // For XlaHostCompute nodes with dependencies, add control edges between
     // them so XlaCompiler can handle them in correct order.
-    for (auto iter : host_compute_nodes) {
+    for (const auto& iter : host_compute_nodes) {
       Node* host_compute_node = iter.second;
       std::vector<string> token_input_node_names;
       TF_RETURN_IF_ERROR(GetNodeAttr(host_compute_node->def(),
@@ -2479,7 +2479,7 @@ Status ExtractOutsideCompilation(
 
       TF_RETURN_IF_ERROR(fld->RemoveFunction(host_graph_func_name));
 
-      for (auto shape_inference_graph_name : shape_inference_graphs) {
+      for (const auto& shape_inference_graph_name : shape_inference_graphs) {
         TF_RETURN_IF_ERROR(RewriteShapeInferenceGraph(
             shape_inference_graph_name, g, pivot_node, fld));
       }
diff --git a/tensorflow/compiler/jit/mark_for_compilation_pass.cc b/tensorflow/compiler/jit/mark_for_compilation_pass.cc
index 30318839908..77496fe7960 100644
--- a/tensorflow/compiler/jit/mark_for_compilation_pass.cc
+++ b/tensorflow/compiler/jit/mark_for_compilation_pass.cc
@@ -1161,7 +1161,7 @@ Status MarkForCompilationPassImpl::FindCompilationCandidates() {
   std::vector<string> vall_ops = XlaOpRegistry::GetAllRegisteredOps();
   absl::flat_hash_set<string> all_ops(vall_ops.begin(), vall_ops.end());
   // Check that user's provided TF operation really exists.
-  for (auto s : whitelist) {
+  for (const auto& s : whitelist) {
     if (!all_ops.contains(string(s))) {
       return errors::InvalidArgument(
           "The operation '", s,
@@ -1475,7 +1475,7 @@ void MarkForCompilationPassImpl::VLogClusteringSummary() {
           << RatioToString(auto_clustering_info.clustered_node_count(),
                            graph_->num_nodes());
 
-  for (XlaAutoClusteringSummary::Cluster cluster :
+  for (const XlaAutoClusteringSummary::Cluster& cluster :
        auto_clustering_info.clusters()) {
     absl::string_view cluster_name = cluster.name();
     int size = cluster.size();
diff --git a/tensorflow/compiler/jit/node_matchers.cc b/tensorflow/compiler/jit/node_matchers.cc
index 867bfe80202..bfdb6e751f5 100644
--- a/tensorflow/compiler/jit/node_matchers.cc
+++ b/tensorflow/compiler/jit/node_matchers.cc
@@ -493,7 +493,7 @@ std::pair<string, AttrValue> impl::AttrLiteralHelper(
     const std::pair<string, absl::Span<const string>>& string_list_attr) {
   AttrValue attr_value;
   AttrValue::ListValue* list = attr_value.mutable_list();
-  for (string s : string_list_attr.second) {
+  for (const string& s : string_list_attr.second) {
     list->add_s(s);
   }
   return {string_list_attr.first, attr_value};
diff --git a/tensorflow/compiler/tf2tensorrt/convert/convert_graph.cc b/tensorflow/compiler/tf2tensorrt/convert/convert_graph.cc
index 3e9a7954b03..278f49da71b 100644
--- a/tensorflow/compiler/tf2tensorrt/convert/convert_graph.cc
+++ b/tensorflow/compiler/tf2tensorrt/convert/convert_graph.cc
@@ -641,7 +641,7 @@ Status ConvertAfterShapes(const ConversionParams& params) {
   // Segment the graph into subgraphs that can be converted to TensorRT
   segment::SegmentOptions segment_options;
   // TODO(ben,jie,sami): exclude output nodes (DISCUSS IT)
-  for (auto node : *(params.output_names)) {
+  for (const auto& node : *(params.output_names)) {
     segment_options.exclude_node_list.insert(node);
   }
   segment_options.minimum_segment_size = params.minimum_segment_size;
diff --git a/tensorflow/compiler/tf2tensorrt/convert/convert_nodes.cc b/tensorflow/compiler/tf2tensorrt/convert/convert_nodes.cc
index 8083a55466a..bb705812c52 100644
--- a/tensorflow/compiler/tf2tensorrt/convert/convert_nodes.cc
+++ b/tensorflow/compiler/tf2tensorrt/convert/convert_nodes.cc
@@ -5738,7 +5738,7 @@ static void RegisterValidatableOpConverters(
        {"FusedBatchNorm", "FusedBatchNormV2", "FusedBatchNormV3"}) {
     (*registration)[normalization_op_type] = ConvertFusedBatchNorm;
   }
-  for (auto unary_op_pair : *UnaryOperationMap()) {
+  for (const auto& unary_op_pair : *UnaryOperationMap()) {
     (*registration)[unary_op_pair.first] = ConvertUnary;
   }
   for (auto reduce_op_type : {"Sum", "Prod", "Max", "Min", "Mean"}) {
diff --git a/tensorflow/compiler/tf2tensorrt/convert/trt_optimization_pass.cc b/tensorflow/compiler/tf2tensorrt/convert/trt_optimization_pass.cc
index d9d8a4461a3..6ab719db54d 100644
--- a/tensorflow/compiler/tf2tensorrt/convert/trt_optimization_pass.cc
+++ b/tensorflow/compiler/tf2tensorrt/convert/trt_optimization_pass.cc
@@ -93,7 +93,7 @@ void TRTOptimizationPass::PrintDebugInfo(grappler::Cluster* cluster,
     const auto dev_names = cluster->GetDeviceNames();
     if (!dev_names.empty()) {
       LOG(INFO) << offset << " Device names:";
-      for (const auto s : dev_names) {
+      for (const auto& s : dev_names) {
         LOG(INFO) << offset2 << s;
       }
     }
@@ -101,7 +101,7 @@ void TRTOptimizationPass::PrintDebugInfo(grappler::Cluster* cluster,
     auto status = cluster->GetPeakMemoryUsage(&peak_mem);
     if (status == Status::OK()) {
       LOG(INFO) << offset << "Peak Memory Usage :";
-      for (auto s : peak_mem) {
+      for (const auto& s : peak_mem) {
         LOG(INFO) << offset2 << s.first << " = " << s.second;
       }
     }
@@ -109,7 +109,7 @@ void TRTOptimizationPass::PrintDebugInfo(grappler::Cluster* cluster,
     const auto dev_props = cluster->GetDevices();
     if (!dev_props.empty()) {
       LOG(INFO) << offset << "Device properties:";
-      for (auto k : dev_props) {
+      for (const auto& k : dev_props) {
         LOG(INFO) << offset2 << k.first;
         const auto& dt = k.second;
         LOG(INFO) << offset3 << "type          = " << dt.type();
@@ -127,7 +127,7 @@ void TRTOptimizationPass::PrintDebugInfo(grappler::Cluster* cluster,
         LOG(INFO) << offset3 << "bandwidth     = " << dt.bandwidth();
         if (dt.environment_size()) {
           LOG(INFO) << offset3 << "environment   :";
-          for (const auto e : dt.environment()) {
+          for (const auto& e : dt.environment()) {
             LOG(INFO) << offset4 << e.first << " = " << e.second;
           }
         }
diff --git a/tensorflow/compiler/tf2xla/functionalize_control_flow.cc b/tensorflow/compiler/tf2xla/functionalize_control_flow.cc
index 4bc1a5dd688..033dae2292d 100644
--- a/tensorflow/compiler/tf2xla/functionalize_control_flow.cc
+++ b/tensorflow/compiler/tf2xla/functionalize_control_flow.cc
@@ -125,7 +125,7 @@ Status FunctionalizeControlFlowForFunction(
       nodes_to_associated_functions.push_back({n, associated_functions});
     }
   }
-  for (auto iter : nodes_to_associated_functions) {
+  for (const auto& iter : nodes_to_associated_functions) {
     Node* n = iter.first;
     auto associated_functions = iter.second;
     for (auto& associated_function : associated_functions) {
diff --git a/tensorflow/compiler/tf2xla/resource_util.cc b/tensorflow/compiler/tf2xla/resource_util.cc
index 74e08060199..3537d09dde6 100644
--- a/tensorflow/compiler/tf2xla/resource_util.cc
+++ b/tensorflow/compiler/tf2xla/resource_util.cc
@@ -141,7 +141,7 @@ Status UpdateResourceUsageFromFunctionBodyAnalysis(
         caller_source_to_path) {
   std::unordered_map<std::string, Node*> node_name_index =
       fbody.graph->BuildNodeNameIndex();
-  for (auto it : called_function_source_to_path) {
+  for (const auto& it : called_function_source_to_path) {
     ResourceUsageAnalysis::NodeInfo src_node_info = it.first;
 
     // If source is an _Arg, then the true source is actually corresponding
@@ -309,7 +309,7 @@ Status AnalyzeResourceUsage(
     }
   }
 
-  for (auto it : user_to_source) {
+  for (const auto& it : user_to_source) {
     (*source_to_path)[it.second].emplace(function_name, it.first->dst()->name(),
                                          it.first->dst()->type_string());
   }
diff --git a/tensorflow/compiler/tf2xla/tf2xla_util.cc b/tensorflow/compiler/tf2xla/tf2xla_util.cc
index 1e164b30766..7475d3b5eac 100644
--- a/tensorflow/compiler/tf2xla/tf2xla_util.cc
+++ b/tensorflow/compiler/tf2xla/tf2xla_util.cc
@@ -621,7 +621,7 @@ Status RewriteAssociatedFunction(
       NodeDebugInfo debug_info(*node);
       NodeDefBuilder builder(node->name(), rewritten_function_name, fld,
                              &debug_info);
-      for (auto attr : node->attrs()) {
+      for (const auto& attr : node->attrs()) {
         builder.Attr(attr.first, attr.second);
       }
       for (int i = 0; i < node->num_inputs(); i++) {
@@ -695,7 +695,7 @@ Status CachedFunctionHandles::GetOrInstantiate(
 
 Status CachedFunctionHandles::ReleaseAllHandles() {
   Status result;
-  for (auto iter : handles_) {
+  for (const auto& iter : handles_) {
     result.Update(flr_->ReleaseHandle(iter.second));
   }
   handles_.clear();
diff --git a/tensorflow/core/common_runtime/buf_rendezvous.cc b/tensorflow/core/common_runtime/buf_rendezvous.cc
index b0780b3a297..6733a2e16a3 100644
--- a/tensorflow/core/common_runtime/buf_rendezvous.cc
+++ b/tensorflow/core/common_runtime/buf_rendezvous.cc
@@ -183,7 +183,7 @@ void BufRendezvous::LogContents() {
   LOG(INFO) << strings::StrCat("BufRendezvous ",
                                strings::Hex(reinterpret_cast<uint64>(this)),
                                " step_id=", step_id_, " current contents:");
-  for (auto it : hook_table_) {
+  for (const auto& it : hook_table_) {
     LOG(INFO) << it.first << ":" << it.second->DebugString();
   }
 }
diff --git a/tensorflow/core/common_runtime/direct_session.cc b/tensorflow/core/common_runtime/direct_session.cc
index 2f5fbd2353c..044d45711cb 100644
--- a/tensorflow/core/common_runtime/direct_session.cc
+++ b/tensorflow/core/common_runtime/direct_session.cc
@@ -1624,7 +1624,7 @@ Status DirectSession::CreateGraphs(
   // Update our current state based on the execution_state's
   // placements.  If there are any mismatches for a node,
   // we should fail, as this should never happen.
-  for (auto placement_pair : current_stateful_placements) {
+  for (const auto& placement_pair : current_stateful_placements) {
     const string& node_name = placement_pair.first;
     const string& placement = placement_pair.second;
     auto iter = stateful_placements_.find(node_name);
diff --git a/tensorflow/core/common_runtime/step_stats_collector.cc b/tensorflow/core/common_runtime/step_stats_collector.cc
index e9f913d72b9..3cac56db776 100644
--- a/tensorflow/core/common_runtime/step_stats_collector.cc
+++ b/tensorflow/core/common_runtime/step_stats_collector.cc
@@ -305,7 +305,7 @@ void StepStatsCollector::BuildCostModel(
     }
   }
 
-  for (auto itr : device_map) {
+  for (const auto& itr : device_map) {
     const StringPiece device = itr.first;
     if (per_device_stats.find(device) == per_device_stats.end()) {
       continue;
diff --git a/tensorflow/core/framework/attr_value_util.cc b/tensorflow/core/framework/attr_value_util.cc
index fb51da9dee2..a307c8a18c1 100644
--- a/tensorflow/core/framework/attr_value_util.cc
+++ b/tensorflow/core/framework/attr_value_util.cc
@@ -216,7 +216,7 @@ string SummarizeTensor(const TensorProto& tensor_proto) {
 
 string SummarizeFunc(const NameAttrList& func) {
   std::vector<string> entries;
-  for (auto p : func.attr()) {
+  for (const auto& p : func.attr()) {
     entries.push_back(
         strings::StrCat(p.first, "=", SummarizeAttrValue(p.second)));
   }
diff --git a/tensorflow/core/framework/collective.cc b/tensorflow/core/framework/collective.cc
index ad9165869a0..0b90adb78f8 100644
--- a/tensorflow/core/framework/collective.cc
+++ b/tensorflow/core/framework/collective.cc
@@ -102,7 +102,7 @@ string CollInstanceParams::ToString() const {
     strings::StrAppend(&v, n, ", ");
   }
   strings::StrAppend(&v, "} num_devices_per_task={");
-  for (const auto dpt : num_devices_per_task) {
+  for (const auto& dpt : num_devices_per_task) {
     strings::StrAppend(&v, dpt.first, ": ", dpt.second, ", ");
   }
   strings::StrAppend(&v, "}, collective_name=", impl_details.collective_name,
diff --git a/tensorflow/core/framework/dataset.cc b/tensorflow/core/framework/dataset.cc
index 24d6bb3bdc9..e99fc951391 100644
--- a/tensorflow/core/framework/dataset.cc
+++ b/tensorflow/core/framework/dataset.cc
@@ -228,7 +228,7 @@ Status GraphDefBuilderWrapper::AddDataset(
     opts.reset(new GraphDefBuilder::Options(
         opts->WithAttr("output_types", dataset->output_dtypes())));
   }
-  for (auto attr : attrs) {
+  for (const auto& attr : attrs) {
     opts.reset(
         new GraphDefBuilder::Options(opts->WithAttr(attr.first, attr.second)));
   }
diff --git a/tensorflow/core/framework/dataset.h b/tensorflow/core/framework/dataset.h
index a909e8594a2..10ea8cb738e 100644
--- a/tensorflow/core/framework/dataset.h
+++ b/tensorflow/core/framework/dataset.h
@@ -250,7 +250,7 @@ class GraphDefBuilderWrapper {
   bool HasAttr(const string& op_type_name, const string& attr_name) const;
 
   bool HasAttr(const OpDef* op_def, const string& attr_name) const {
-    for (auto attr : op_def->attr()) {
+    for (const auto& attr : op_def->attr()) {
       if (attr.name() == attr_name) {
         return true;
       }
diff --git a/tensorflow/core/framework/function_handle_cache.cc b/tensorflow/core/framework/function_handle_cache.cc
index b64161d50b3..16b3fa95114 100644
--- a/tensorflow/core/framework/function_handle_cache.cc
+++ b/tensorflow/core/framework/function_handle_cache.cc
@@ -57,7 +57,7 @@ Status FunctionHandleCache::Instantiate(
 
 Status FunctionHandleCache::Clear() {
   mutex_lock l(mu_);
-  for (auto entry : handles_) {
+  for (const auto& entry : handles_) {
     TF_RETURN_IF_ERROR(lib_->ReleaseHandle(entry.second));
   }
   handles_.clear();
diff --git a/tensorflow/core/framework/function_testlib.cc b/tensorflow/core/framework/function_testlib.cc
index d1562169915..5919ed7831b 100644
--- a/tensorflow/core/framework/function_testlib.cc
+++ b/tensorflow/core/framework/function_testlib.cc
@@ -53,7 +53,8 @@ NodeDef NDef(StringPiece name, StringPiece op, gtl::ArraySlice<string> inputs,
   n.set_op(string(op));
   for (const auto& in : inputs) n.add_input(in);
   n.set_device(device);
-  for (auto na : attrs) n.mutable_attr()->insert({na.first, na.second.proto});
+  for (const auto& na : attrs)
+    n.mutable_attr()->insert({na.first, na.second.proto});
   return n;
 }
 
diff --git a/tensorflow/core/framework/op_segment.cc b/tensorflow/core/framework/op_segment.cc
index f7e194baeed..5d7ca776fbc 100644
--- a/tensorflow/core/framework/op_segment.cc
+++ b/tensorflow/core/framework/op_segment.cc
@@ -26,13 +26,13 @@ limitations under the License.
 namespace tensorflow {
 
 OpSegment::Item::~Item() {
-  for (auto kv : name_kernel) delete kv.second;
+  for (const auto& kv : name_kernel) delete kv.second;
 }
 
 OpSegment::OpSegment() {}
 
 OpSegment::~OpSegment() {
-  for (auto kv : sessions_) delete kv.second;
+  for (const auto& kv : sessions_) delete kv.second;
 }
 
 Status OpSegment::FindOrCreate(const string& session_handle,
diff --git a/tensorflow/lite/experimental/support/codegen/android_java_generator.cc b/tensorflow/lite/experimental/support/codegen/android_java_generator.cc
index b16db570aaa..b0ac31c2fce 100644
--- a/tensorflow/lite/experimental/support/codegen/android_java_generator.cc
+++ b/tensorflow/lite/experimental/support/codegen/android_java_generator.cc
@@ -275,7 +275,7 @@ bool GenerateWrapperImports(CodeWriter* code_writer, const ModelInfo& model,
   }
 
   std::sort(imports.begin(), imports.end());
-  for (const auto target : imports) {
+  for (const auto& target : imports) {
     code_writer->SetTokenValue("TARGET", target);
     code_writer->Append("import {{TARGET}};");
   }
diff --git a/tensorflow/lite/experimental/support/codegen/code_generator.cc b/tensorflow/lite/experimental/support/codegen/code_generator.cc
index 687724815ef..39c0bd86d89 100644
--- a/tensorflow/lite/experimental/support/codegen/code_generator.cc
+++ b/tensorflow/lite/experimental/support/codegen/code_generator.cc
@@ -42,7 +42,7 @@ void ResolveConflictedNamesByAddingIndex(std::vector<std::string>* names_ptr) {
       names[i].append(std::to_string(indexes[names[i]]));
     }
   }
-  for (const auto it : first_appearance) {
+  for (const auto& it : first_appearance) {
     const auto& name = it.first;
     const auto i = it.second;
     if (indexes[name] > 1) {
@@ -148,11 +148,11 @@ void CodeGenerator::ResolveConflictedInputAndOutputNames(
   std::unordered_set<std::string> io_conflict;
   auto& input_names = *inputs;
   auto& output_names = *outputs;
-  for (const auto input : input_names) {
+  for (const auto& input : input_names) {
     if (io_conflict.find(input) != io_conflict.end()) {
       continue;
     }
-    for (const auto output : output_names) {
+    for (const auto& output : output_names) {
       if (input == output) {
         io_conflict.insert(input);
         break;
diff --git a/tensorflow/lite/experimental/writer/option_writer_generator.cc b/tensorflow/lite/experimental/writer/option_writer_generator.cc
index 0ae895ffb51..a565422457c 100644
--- a/tensorflow/lite/experimental/writer/option_writer_generator.cc
+++ b/tensorflow/lite/experimental/writer/option_writer_generator.cc
@@ -197,7 +197,7 @@ class OpOptionData {
     option_to_struct_["MirrorPadOptions"] = "TfLiteMirrorPaddingParams";
     // Now for every op, try to find an option.
     bool fatal = false;
-    for (auto op_name : ops_) {
+    for (const auto& op_name : ops_) {
       bool found_option = false;
       auto d = tflite::BuiltinOptionsTypeTable();
       std::string collapsed_option_name_guess =
diff --git a/tensorflow/lite/experimental/writer/writer_lib.cc b/tensorflow/lite/experimental/writer/writer_lib.cc
index a88544e95b1..85f57527c31 100644
--- a/tensorflow/lite/experimental/writer/writer_lib.cc
+++ b/tensorflow/lite/experimental/writer/writer_lib.cc
@@ -224,7 +224,7 @@ SubgraphWriter::ExportBuffers(flatbuffers::FlatBufferBuilder* fbb) {
 flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<OperatorCode>>>
 SubgraphWriter::CreateOpCodeTable(flatbuffers::FlatBufferBuilder* fbb) {
   std::vector<flatbuffers::Offset<OperatorCode>> codes;
-  for (auto it : opcodes_) {
+  for (const auto& it : opcodes_) {
     const char* custom_name = it.custom.empty() ? nullptr : it.custom.c_str();
     codes.push_back(CreateOperatorCodeDirect(
         *fbb, static_cast<BuiltinOperator>(it.builtin), custom_name));
diff --git a/tensorflow/tools/graph_transforms/quantize_nodes.cc b/tensorflow/tools/graph_transforms/quantize_nodes.cc
index 40ca677480f..a03553af8f1 100644
--- a/tensorflow/tools/graph_transforms/quantize_nodes.cc
+++ b/tensorflow/tools/graph_transforms/quantize_nodes.cc
@@ -218,8 +218,8 @@ Status MergeDuplicateNodes(const GraphDef& input_graph_def,
     // duplicates and can be removed, unless they're stateful.
     std::map<string, string> inputs_to_rename;
     GraphDef merged_graph_def;
-    for (const std::pair<uint64, std::vector<const NodeDef*>> hashed_node_info :
-         hashed_nodes) {
+    for (const std::pair<const uint64, std::vector<const NodeDef*>>&
+             hashed_node_info : hashed_nodes) {
       const std::vector<const NodeDef*>& hash_node_list =
           hashed_node_info.second;
       for (int i = 0; i < hash_node_list.size(); ++i) {
diff --git a/tensorflow/tools/graph_transforms/sparsify_gather.cc b/tensorflow/tools/graph_transforms/sparsify_gather.cc
index cc4078dfb85..9aaf9b98e19 100644
--- a/tensorflow/tools/graph_transforms/sparsify_gather.cc
+++ b/tensorflow/tools/graph_transforms/sparsify_gather.cc
@@ -478,7 +478,7 @@ Status SparsifyGatherInternal(
     }
 
     // Add nodes with a reference count of 0 for deletion.
-    for (auto entry : refs) {
+    for (const auto& entry : refs) {
       if (entry.second == 0) {
         removed_node_names.push_back(entry.first);
       }