diff --git a/include/tvm/runtime/container.h b/include/tvm/runtime/container.h
index 50b406b2c030d..083f87f89bc9d 100644
--- a/include/tvm/runtime/container.h
+++ b/include/tvm/runtime/container.h
@@ -360,7 +360,15 @@ class String : public ObjectRef {
    * \note If user passes const reference, it will trigger copy. If it's rvalue,
    * it will be moved into other.
    */
-  explicit String(std::string other);
+  String(std::string other);  // NOLINT(*)
+
+  /*!
+   * \brief Construct a new String object
+   *
+   * \param other a char array.
+   */
+  String(const char* other)  // NOLINT(*)
+      : String(std::string(other)) {}
 
   /*!
    * \brief Change the value the reference object points to.
diff --git a/src/node/serialization.cc b/src/node/serialization.cc
index 97436bae242c9..81b7b255266fd 100644
--- a/src/node/serialization.cc
+++ b/src/node/serialization.cc
@@ -53,6 +53,8 @@ class NodeIndexer : public AttrVisitor {
   std::vector<Object*> node_list_{nullptr};
   std::unordered_map<DLTensor*, size_t> tensor_index_;
   std::vector<DLTensor*> tensor_list_;
+  std::unordered_map<StringObj*, size_t> string_index_;
+  std::vector<std::string> string_list_;
   ReflectionVTable* reflection_ = ReflectionVTable::Global();
 
   void Visit(const char* key, double* value) final {}
@@ -102,7 +104,13 @@ class NodeIndexer : public AttrVisitor {
       for (const auto& kv : n->data) {
         MakeIndex(const_cast<Object*>(kv.second.get()));
       }
-    } else if (!node->IsInstance<StringObj>()) {
+    } else if (node->IsInstance<StringObj>()) {
+      StringObj* ptr = static_cast<StringObj*>(node);
+      if (string_index_.count(ptr)) return;
+      CHECK_EQ(string_index_.size(), string_list_.size());
+      string_index_[ptr] = string_list_.size();
+      string_list_.push_back(ptr->data);
+    } else {
       reflection_->VisitAttrs(node, this);
     }
   }
@@ -337,11 +345,7 @@ class JSONAttrSetter : public AttrVisitor {
         n->data[node_->keys[i]]
             = ObjectRef(node_list_->at(node_->data[i]));
       }
-    } else if (node->IsInstance<StringObj>()) {
-      StringObj* n = static_cast<StringObj*>(node);
-      auto saved = node_list_->at(node_->data[0]);
-      saved = runtime::GetObjectPtr<StringObj>(n);
-    } else {
+    } else if (!node->IsInstance<StringObj>()) {
       reflection_->VisitAttrs(node, this);
     }
   }
@@ -355,6 +359,8 @@ struct JSONGraph {
   std::vector<JSONNode> nodes;
   // base64 b64ndarrays of arrays
   std::vector<std::string> b64ndarrays;
+  // strings
+  std::vector<std::string> strings;
   // global attributes
   AttrMap attrs;
 
@@ -363,6 +369,7 @@ struct JSONGraph {
     writer->WriteObjectKeyValue("root", root);
     writer->WriteObjectKeyValue("nodes", nodes);
     writer->WriteObjectKeyValue("b64ndarrays", b64ndarrays);
+    writer->WriteObjectKeyValue("strings", strings);
     if (attrs.size() != 0) {
       writer->WriteObjectKeyValue("attrs", attrs);
     }
@@ -375,6 +382,7 @@ struct JSONGraph {
     helper.DeclareField("root", &root);
     helper.DeclareField("nodes", &nodes);
     helper.DeclareOptionalField("b64ndarrays", &b64ndarrays);
+    helper.DeclareOptionalField("strings", &strings);
     helper.DeclareOptionalField("attrs", &attrs);
     helper.ReadAllFields(reader);
   }
@@ -403,6 +411,8 @@ struct JSONGraph {
       b64strm.Finish();
       g.b64ndarrays.emplace_back(std::move(blob));
     }
+    // serialize string
+    g.strings = std::move(indexer.string_list_);
     return g;
   }
 };
@@ -423,6 +433,7 @@ ObjectRef LoadJSON(std::string json_str) {
   jgraph.Load(&reader);
   std::vector<ObjectPtr<Object> > nodes;
   std::vector<runtime::NDArray> tensors;
+  std::vector<std::string> strings;
   // load in tensors
   for (const std::string& blob : jgraph.b64ndarrays) {
     dmlc::MemoryStringStream mstrm(const_cast<std::string*>(&blob));
@@ -432,16 +443,25 @@ ObjectRef LoadJSON(std::string json_str) {
     CHECK(temp.Load(&b64strm));
     tensors.emplace_back(temp);
   }
+  // load in strings
+  strings = std::move(jgraph.strings);
   ReflectionVTable* reflection = ReflectionVTable::Global();
 
   // node 0 is always null
   nodes.reserve(jgraph.nodes.size());
 
+  int string_idx = 0;
   for (const JSONNode& jnode : jgraph.nodes) {
     if (jnode.type_key.length() != 0) {
-      ObjectPtr<Object> node =
-          reflection->CreateInitObject(jnode.type_key, jnode.global_key);
-      nodes.emplace_back(node);
+      if (jnode.type_key == "runtime.String") {
+        String ref = String(strings[string_idx++]);
+        auto* ref_node = const_cast<StringObj*>(ref.as<StringObj>());
+        nodes.emplace_back(runtime::GetObjectPtr<Object>(ref_node));
+      } else {
+        ObjectPtr<Object> node =
+            reflection->CreateInitObject(jnode.type_key, jnode.global_key);
+        nodes.emplace_back(node);
+      }
     } else {
       nodes.emplace_back(ObjectPtr<Object>());
     }
diff --git a/src/relay/backend/build_module.cc b/src/relay/backend/build_module.cc
index bc0685b5d9053..6e6faf9274ef7 100644
--- a/src/relay/backend/build_module.cc
+++ b/src/relay/backend/build_module.cc
@@ -272,7 +272,7 @@ class RelayBuildModule : public runtime::ModuleNode {
     }
 
     Array<Pass> pass_seqs;
-    Array<runtime::String> entry_functions{runtime::String("main")};
+    Array<runtime::String> entry_functions{"main"};
     pass_seqs.push_back(transform::RemoveUnusedFunctions(entry_functions));
 
     // Run all dialect legalization passes.
diff --git a/src/relay/transforms/alter_op_layout.cc b/src/relay/transforms/alter_op_layout.cc
index 59cf9f98288f9..aab0b3a30a7cf 100644
--- a/src/relay/transforms/alter_op_layout.cc
+++ b/src/relay/transforms/alter_op_layout.cc
@@ -125,8 +125,7 @@ Pass AlterOpLayout() {
     [=](Function f, IRModule m, PassContext pc) {
       return Downcast<Function>(relay::alter_op_layout::AlterOpLayout(f));
   };
-  return CreateFunctionPass(pass_func, 3, "AlterOpLayout",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 3, "AlterOpLayout", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.AlterOpLayout")
diff --git a/src/relay/transforms/annotate_target.cc b/src/relay/transforms/annotate_target.cc
index 65e17fcefddb8..44ef35a285f56 100644
--- a/src/relay/transforms/annotate_target.cc
+++ b/src/relay/transforms/annotate_target.cc
@@ -226,7 +226,7 @@ Pass AnnotateTarget(const std::string& target) {
         return Downcast<Function>(relay::annotate_target::AnnotateTarget(f, target));
       };
   auto func_pass = CreateFunctionPass(pass_func, 0, "AnnotateTargetFunc",
-                                      {runtime::String("InferType")});
+                                      {"InferType"});
   return transform::Sequential({func_pass, InferType()}, "AnnotateTarget");
 }
 
diff --git a/src/relay/transforms/canonicalize_cast.cc b/src/relay/transforms/canonicalize_cast.cc
index 4b35ba219b674..ebcbd578b5f0b 100644
--- a/src/relay/transforms/canonicalize_cast.cc
+++ b/src/relay/transforms/canonicalize_cast.cc
@@ -133,8 +133,7 @@ Pass CanonicalizeCast() {
     [=](Function f, IRModule m, PassContext pc) {
     return Downcast<Function>(CanonicalizeCast(f));
   };
-  return CreateFunctionPass(pass_func, 3, "CanonicalizeCast",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 3, "CanonicalizeCast", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.CanonicalizeCast")
diff --git a/src/relay/transforms/canonicalize_ops.cc b/src/relay/transforms/canonicalize_ops.cc
index 44140a902a2fd..1d3111b29d7d5 100644
--- a/src/relay/transforms/canonicalize_ops.cc
+++ b/src/relay/transforms/canonicalize_ops.cc
@@ -74,8 +74,7 @@ Pass CanonicalizeOps() {
     [=](Function f, IRModule m, PassContext pc) {
     return Downcast<Function>(CanonicalizeOps(f));
   };
-  return CreateFunctionPass(pass_func, 3, "CanonicalizeOps",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 3, "CanonicalizeOps", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.CanonicalizeOps")
diff --git a/src/relay/transforms/combine_parallel_conv2d.cc b/src/relay/transforms/combine_parallel_conv2d.cc
index 3c8eea04d28f3..af6b1353f5acf 100644
--- a/src/relay/transforms/combine_parallel_conv2d.cc
+++ b/src/relay/transforms/combine_parallel_conv2d.cc
@@ -220,8 +220,7 @@ Pass CombineParallelConv2D(uint64_t min_num_branches) {
     [=](Function f, IRModule m, PassContext pc) {
       return Downcast<Function>(CombineParallelConv2D(f, min_num_branches));
   };
-  return CreateFunctionPass(pass_func, 4, "CombineParallelConv2d",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 4, "CombineParallelConv2d", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.CombineParallelConv2D")
diff --git a/src/relay/transforms/combine_parallel_dense.cc b/src/relay/transforms/combine_parallel_dense.cc
index 2dc8321e517b2..1278020ac7353 100644
--- a/src/relay/transforms/combine_parallel_dense.cc
+++ b/src/relay/transforms/combine_parallel_dense.cc
@@ -80,8 +80,7 @@ Pass CombineParallelDense(uint64_t min_num_branches) {
     [=](Function f, IRModule m, PassContext pc) {
       return Downcast<Function>(CombineParallelDense(f, min_num_branches));
   };
-  return CreateFunctionPass(pass_func, 4, "CombineParallelDense",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 4, "CombineParallelDense", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.CombineParallelDense")
diff --git a/src/relay/transforms/combine_parallel_op_batch.cc b/src/relay/transforms/combine_parallel_op_batch.cc
index f63f169be4086..361565ef11d76 100644
--- a/src/relay/transforms/combine_parallel_op_batch.cc
+++ b/src/relay/transforms/combine_parallel_op_batch.cc
@@ -193,8 +193,7 @@ Pass CombineParallelOpBatch(const std::string& op_name,
                                                        batch_op_name,
                                                        min_num_branches));
   };
-  return CreateFunctionPass(pass_func, 4, "CombineParallelOpBatch",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 4, "CombineParallelOpBatch", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.CombineParallelOpBatch")
diff --git a/src/relay/transforms/convert_layout.cc b/src/relay/transforms/convert_layout.cc
index d43a0851e0997..dbb2c38e3f274 100644
--- a/src/relay/transforms/convert_layout.cc
+++ b/src/relay/transforms/convert_layout.cc
@@ -133,9 +133,7 @@ Pass ConvertLayout(const std::string& desired_layout) {
         return Downcast<Function>(relay::convert_op_layout::ConvertLayout(f, desired_layout));
       };
   return CreateFunctionPass(
-      pass_func, 3, "ConvertLayout",
-      {runtime::String("InferType"),
-       runtime::String("CanonicalizeOps")});
+      pass_func, 3, "ConvertLayout", {"InferType", "CanonicalizeOps"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.ConvertLayout").set_body_typed(ConvertLayout);
diff --git a/src/relay/transforms/device_annotation.cc b/src/relay/transforms/device_annotation.cc
index 9955ef6ee7d2c..908ba87a8c521 100644
--- a/src/relay/transforms/device_annotation.cc
+++ b/src/relay/transforms/device_annotation.cc
@@ -573,8 +573,7 @@ Pass RewriteAnnotatedOps(int fallback_device) {
     [=](Function f, IRModule m, PassContext pc) {
     return Downcast<Function>(relay::RewriteAnnotatedOps(f, fallback_device));
   };
-  return CreateFunctionPass(pass_func, 1, "RewriteAnnotatedOps",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 1, "RewriteAnnotatedOps", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.RewriteDeviceAnnotation")
diff --git a/src/relay/transforms/eliminate_common_subexpr.cc b/src/relay/transforms/eliminate_common_subexpr.cc
index 696e83a7db538..68c59f5ea2ef1 100644
--- a/src/relay/transforms/eliminate_common_subexpr.cc
+++ b/src/relay/transforms/eliminate_common_subexpr.cc
@@ -91,8 +91,7 @@ Pass EliminateCommonSubexpr(PackedFunc fskip) {
     [=](Function f, IRModule m, PassContext pc) {
       return Downcast<Function>(EliminateCommonSubexpr(f, fskip));
   };
-  return CreateFunctionPass(pass_func, 3, "EliminateCommonSubexpr",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 3, "EliminateCommonSubexpr", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.EliminateCommonSubexpr")
diff --git a/src/relay/transforms/fast_math.cc b/src/relay/transforms/fast_math.cc
index 668982e561e88..8234dea5e075f 100644
--- a/src/relay/transforms/fast_math.cc
+++ b/src/relay/transforms/fast_math.cc
@@ -70,8 +70,7 @@ Pass FastMath() {
     [=](Function f, IRModule m, PassContext pc) {
     return Downcast<Function>(FastMath(f));
   };
-  return CreateFunctionPass(pass_func, 4, "FastMath",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 4, "FastMath", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.FastMath")
diff --git a/src/relay/transforms/fold_scale_axis.cc b/src/relay/transforms/fold_scale_axis.cc
index 11325f6526b84..cfe74bfd8ef16 100644
--- a/src/relay/transforms/fold_scale_axis.cc
+++ b/src/relay/transforms/fold_scale_axis.cc
@@ -960,8 +960,7 @@ Pass ForwardFoldScaleAxis() {
       return Downcast<Function>(
           relay::fold_scale_axis::ForwardFoldScaleAxis(f));
   };
-  return CreateFunctionPass(pass_func, 3, "ForwardFoldScaleAxis",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 3, "ForwardFoldScaleAxis", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.ForwardFoldScaleAxis")
@@ -973,8 +972,7 @@ Pass BackwardFoldScaleAxis() {
       return Downcast<Function>(
           relay::fold_scale_axis::BackwardFoldScaleAxis(f));
     };
-  return CreateFunctionPass(pass_func, 3, "BackwardFoldScaleAxis",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 3, "BackwardFoldScaleAxis", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.BackwardFoldScaleAxis")
diff --git a/src/relay/transforms/fuse_ops.cc b/src/relay/transforms/fuse_ops.cc
index cdd29394a2047..f646042962f0c 100644
--- a/src/relay/transforms/fuse_ops.cc
+++ b/src/relay/transforms/fuse_ops.cc
@@ -980,8 +980,7 @@ Pass FuseOps(int fuse_opt_level) {
     int opt_level = fuse_opt_level == -1 ? pc->opt_level : fuse_opt_level;
     return Downcast<Function>(FuseOps(f, opt_level, m));
   };
-  return CreateFunctionPass(pass_func, 1, "FuseOps",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 1, "FuseOps", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.FuseOps")
diff --git a/src/relay/transforms/legalize.cc b/src/relay/transforms/legalize.cc
index b7a0945951295..0cb1c7d9b51db 100644
--- a/src/relay/transforms/legalize.cc
+++ b/src/relay/transforms/legalize.cc
@@ -102,7 +102,7 @@ Pass Legalize(const std::string& legalize_map_attr_name) {
       [=](Function f, IRModule m, PassContext pc) {
         return Downcast<Function>(relay::legalize::Legalize(f, legalize_map_attr_name));
       };
-  return CreateFunctionPass(pass_func, 1, "Legalize", {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 1, "Legalize", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.Legalize").set_body_typed(Legalize);
diff --git a/src/relay/transforms/simplify_inference.cc b/src/relay/transforms/simplify_inference.cc
index b33799a26b430..d349fdddeeea8 100644
--- a/src/relay/transforms/simplify_inference.cc
+++ b/src/relay/transforms/simplify_inference.cc
@@ -204,8 +204,7 @@ Pass SimplifyInference() {
     [=](Function f, IRModule m, PassContext pc) {
     return Downcast<Function>(SimplifyInference(f));
   };
-  return CreateFunctionPass(pass_func, 0, "SimplifyInference",
-                            {runtime::String("InferType")});
+  return CreateFunctionPass(pass_func, 0, "SimplifyInference", {"InferType"});
 }
 
 TVM_REGISTER_GLOBAL("relay._transform.SimplifyInference")
diff --git a/tests/cpp/container_test.cc b/tests/cpp/container_test.cc
index f1198e7274016..063247db09b66 100644
--- a/tests/cpp/container_test.cc
+++ b/tests/cpp/container_test.cc
@@ -261,7 +261,7 @@ TEST(String, empty) {
   using namespace std;
   String s{"hello"};
   CHECK_EQ(s.empty(), false);
-  s = "";
+  s = std::string("");
   CHECK_EQ(s.empty(), true);
 }
 
diff --git a/tests/python/relay/test_ir_nodes.py b/tests/python/relay/test_ir_nodes.py
index f182cbaae6315..5a71023e5d602 100644
--- a/tests/python/relay/test_ir_nodes.py
+++ b/tests/python/relay/test_ir_nodes.py
@@ -25,9 +25,7 @@
 
 def check_json_roundtrip(node):
     json_str = tvm.ir.save_json(node)
-    print(node)
     back = tvm.ir.load_json(json_str)
-    print(back)
     assert tvm.ir.structural_equal(back, node, map_free_vars=True)
 
 
@@ -99,11 +97,13 @@ def test_function():
     type_params = tvm.runtime.convert([])
     fn = relay.Function(params, body, ret_type, type_params)
     fn = fn.with_attr("test_attribute", "value")
+    fn = fn.with_attr("test_attribute1", "value1")
     assert fn.params == params
     assert fn.body == body
     assert fn.type_params == type_params
     assert fn.span == None
     assert fn.attrs["test_attribute"] == "value"
+    assert fn.attrs["test_attribute1"] == "value1"
     str(fn)
     check_json_roundtrip(fn)