diff --git a/CMakeLists.txt b/CMakeLists.txt
index 62aa6db6e46d..930f18aa209d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -255,6 +255,8 @@ include(cmake/modules/LLVM.cmake)
 include(cmake/modules/Micro.cmake)
 include(cmake/modules/ANTLR.cmake)
 include(cmake/modules/contrib/BLAS.cmake)
+include(cmake/modules/contrib/CODEGENC.cmake)
+include(cmake/modules/contrib/DNNL.cmake)
 include(cmake/modules/contrib/Random.cmake)
 include(cmake/modules/contrib/MicroStandaloneRuntime.cmake)
 include(cmake/modules/contrib/Sort.cmake)
diff --git a/cmake/config.cmake b/cmake/config.cmake
index dbad944c5459..42c19b5277be 100644
--- a/cmake/config.cmake
+++ b/cmake/config.cmake
@@ -175,6 +175,10 @@ set(USE_SORT ON)
 # Whether use TensorRT
 # /path/to/tensorrt that contains include and lib dirs
 set(USE_TENSORRT OFF)
+
+# Whether use MKL-DNN (DNNL) codegen
+set(USE_DNNL_CODEGEN OFF)
+
 # Build ANTLR parser for Relay text format
 # Possible values:
 # - ON: enable ANTLR by searching default locations (cmake find_program for antlr4 and /usr/local for jar)
diff --git a/cmake/modules/contrib/CODEGENC.cmake b/cmake/modules/contrib/CODEGENC.cmake
new file mode 100644
index 000000000000..bb53621f1a11
--- /dev/null
+++ b/cmake/modules/contrib/CODEGENC.cmake
@@ -0,0 +1,20 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+file(GLOB CSOURCE_RELAY_CONTRIB_SRC src/relay/backend/contrib/codegen_c/codegen.cc)
+list(APPEND COMPILER_SRCS ${CSOURCE_RELAY_CONTRIB_SRC})
+
diff --git a/cmake/modules/contrib/DNNL.cmake b/cmake/modules/contrib/DNNL.cmake
new file mode 100644
index 000000000000..3fd3f7cbc887
--- /dev/null
+++ b/cmake/modules/contrib/DNNL.cmake
@@ -0,0 +1,28 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+if(USE_DNNL_CODEGEN STREQUAL "ON")
+  file(GLOB DNNL_RELAY_CONTRIB_SRC src/relay/backend/contrib/dnnl/codegen.cc)
+  list(APPEND COMPILER_SRCS ${DNNL_RELAY_CONTRIB_SRC})
+
+  find_library(EXTERN_LIBRARY_DNNL dnnl)
+  list(APPEND TVM_RUNTIME_LINKER_LIBS ${EXTERN_LIBRARY_DNNL})
+  file(GLOB DNNL_CONTRIB_SRC src/runtime/contrib/dnnl/*)
+  list(APPEND RUNTIME_SRCS ${DNNL_CONTRIB_SRC})
+  message(STATUS "Build with DNNL codegen: " ${EXTERN_LIBRARY_DNNL})
+endif()
+
diff --git a/include/tvm/build_module.h b/include/tvm/build_module.h
index a83288ce3662..fba929cda1be 100644
--- a/include/tvm/build_module.h
+++ b/include/tvm/build_module.h
@@ -170,6 +170,9 @@ TVM_DLL Target intel_graphics(const std::vector<std::string>& options =
 TVM_DLL Target stackvm(const std::vector<std::string>& options =
                       std::vector<std::string>());
 
+/*! \return A target for external device */
+TVM_DLL Target ext_dev(const std::vector<std::string>& options =
+                   std::vector<std::string>());
 }  // namespace target
 
 /*!
diff --git a/include/tvm/relay/expr.h b/include/tvm/relay/expr.h
index 2aa88099a69c..01a73d5396cc 100644
--- a/include/tvm/relay/expr.h
+++ b/include/tvm/relay/expr.h
@@ -268,6 +268,15 @@ class FunctionNode : public ExprNode {
    */
   bool IsPrimitive() const;
 
+  /*!
+   * \brief Check whether the function should use the TVM default compiler to build, or
+   * use other compilers.
+   *
+   * \return Whether the function will be compiled using the default compiler
+   * (e.g. those are used in the TVM stack).
+   */
+  bool UseDefaultCompiler() const;
+
   TVM_DLL static Function make(tvm::Array<Var> params,
                                Expr body,
                                Type ret_type,
@@ -588,6 +597,25 @@ std::string AsText(const NodeRef& node,
                    bool show_meta_data = true,
                    runtime::TypedPackedFunc<std::string(Expr)> annotate = nullptr);
 
+/*! \brief namespace of the attributes that are attached to a function. */
+namespace attr {
+/*! \brief Mark the function as a primitive function. */
+constexpr const char* kPrimitive = "Primitive";
+/*!
+ * \brief Indicate the compiler that should be used for builing this function.
+ * When this is unset or set to "default", the default compilation pipeline will be used.
+ */
+constexpr const char* kCompiler = "Compiler";
+/*! \brief Indicate if the function is a closure. */
+constexpr const char* kClosure = "Closure";
+/*! \brief Store a Var to parameter/Constant mapping on a Function. */
+constexpr const char* kParams = "__params__";
+/*! \brief Store the unique external symbol for external compilers. */
+constexpr const char* kExternalSymbol = "ExternalSymbol";
+/*! \brief Mark if the function should be avoided being optimized. */
+constexpr const char* kSkipOptimization = "SkipOptimization";
+}  // namespace attr
+
 }  // namespace relay
 }  // namespace tvm
 #endif  // TVM_RELAY_EXPR_H_
diff --git a/python/tvm/module.py b/python/tvm/module.py
index fb350a2d131e..515fc9ccf7fc 100644
--- a/python/tvm/module.py
+++ b/python/tvm/module.py
@@ -151,7 +151,16 @@ def export_library(self,
         self.save(path_obj)
         files = [path_obj]
         is_system_lib = self.type_key == "llvm" and self.get_function("__tvm_is_system_module")()
+        has_imported_c_file = False
         if self.imported_modules:
+            for i, m in enumerate(self.imported_modules):
+                if m.type_key == "c":
+                    has_imported_c_file = True
+                    c_file_name = "tmp_" + str(i) + ".cc"
+                    path_cc = temp.relpath(c_file_name)
+                    with open(path_cc, "w") as f:
+                        f.write(m.get_source())
+                    files.append(path_cc)
             path_cc = temp.relpath("devc.cc")
             with open(path_cc, "w") as f:
                 f.write(_PackImportsToC(self, is_system_lib))
@@ -161,7 +170,7 @@ def export_library(self,
                 fcompile = _tar.tar
             else:
                 fcompile = _cc.create_shared
-        if self.type_key == "c":
+        if self.type_key == "c" or has_imported_c_file:
             options = []
             if "options" in kwargs:
                 opts = kwargs["options"]
diff --git a/src/codegen/build_module.cc b/src/codegen/build_module.cc
index 80fd57af66f9..a7325a92f50a 100644
--- a/src/codegen/build_module.cc
+++ b/src/codegen/build_module.cc
@@ -309,6 +309,10 @@ Target intel_graphics(const std::vector<std::string>& options) {
 Target stackvm(const std::vector<std::string>& options) {
   return CreateTarget("stackvm", options);
 }
+
+Target ext_dev(const std::vector<std::string>& options) {
+  return CreateTarget("ext_dev", options);
+}
 }  // namespace target
 
 bool LLVMEnabled() {
diff --git a/src/codegen/codegen.cc b/src/codegen/codegen.cc
index ded8fcebf57c..6ce76f60e0e3 100644
--- a/src/codegen/codegen.cc
+++ b/src/codegen/codegen.cc
@@ -69,6 +69,7 @@ std::string PackImportsToC(const runtime::Module& mod, bool system_lib) {
         << "Only support simply one-level hierarchy";
     std::string tkey = im->type_key();
     stream->Write(tkey);
+    if (tkey == "c") continue;
     im->SaveToBinary(stream);
   }
   // translate to C program
diff --git a/src/relay/backend/build_module.cc b/src/relay/backend/build_module.cc
index 9254c7e3e7b9..36139080682e 100644
--- a/src/relay/backend/build_module.cc
+++ b/src/relay/backend/build_module.cc
@@ -73,6 +73,10 @@ struct GraphCodegen {
     return CallFunc<std::string>("get_graph_json", nullptr);
   }
 
+  Array<tvm::runtime::Module> GetExternalModules() {
+    return CallFunc<Array<tvm::runtime::Module> >("get_external_modules", nullptr);
+  }
+
   Map<std::string, Array<LoweredFunc> > GetLoweredFunc() {
     return CallFunc<Map<std::string, Array<LoweredFunc> > >("get_lowered_funcs", nullptr);
   }
@@ -148,6 +152,10 @@ class RelayBuildModule : public runtime::ModuleNode {
       return PackedFunc([sptr_to_self, this](TVMArgs args, TVMRetValue* rv) {
           *rv = this->graph_codegen_->GetLoweredFunc();
       });
+    } else if (name == "get_external_modules") {
+      return PackedFunc([sptr_to_self, this](TVMArgs args, TVMRetValue* rv) {
+          *rv = this->graph_codegen_->GetExternalModules();
+      });
     } else if (name == "optimize") {
       return PackedFunc([sptr_to_self, this](TVMArgs args, TVMRetValue* rv) {
         CHECK_EQ(args.num_args, 2);
@@ -474,6 +482,20 @@ class RelayBuildModule : public runtime::ModuleNode {
         target_host_,
         BuildConfig::Current());
     }
+    Array<tvm::runtime::Module> ext_mods = graph_codegen_->GetExternalModules();
+    if (!ext_mods.empty()) {
+      CHECK(lowered_funcs.size() > 0 || ext_mods.size() == 1)
+          << "Expect to have a TVM DSOModule when multiple external runtime modules exist";
+      if (lowered_funcs.size() == 0) {
+        // Execute the whole module using external runtime.
+        ret_.mod = ext_mods[0];
+      } else {
+        // Import all external runtime modules.
+        for (const auto& it : ext_mods) {
+          ret_.mod.Import(it);
+        }
+      }
+    }
   }
 
  protected:
diff --git a/src/relay/backend/compile_engine.cc b/src/relay/backend/compile_engine.cc
index 083fa5d5610c..9953a05668cf 100644
--- a/src/relay/backend/compile_engine.cc
+++ b/src/relay/backend/compile_engine.cc
@@ -27,6 +27,7 @@
 #include <tvm/runtime/registry.h>
 #include <tvm/relay/attrs/device_copy.h>
 #include <tvm/relay/analysis.h>
+#include <tvm/relay/expr.h>
 #include <tvm/relay/expr_functor.h>
 #include <tvm/relay/op_attr_types.h>
 #include <topi/tags.h>
@@ -608,6 +609,46 @@ class CompileEngineImpl : public CompileEngineNode {
     return LowerShapeFuncInternal(key)->cached_func;
   }
 
+  Array<tvm::runtime::Module> LowerExternalFunctions() {
+    std::unordered_map<std::string, relay::Module> ext_mods;
+    std::vector<CCacheKey> cached_ext_funcs;
+    for (const auto& it : cache_) {
+      auto src_func = it.first->source_func;
+      CHECK(src_func.defined());
+      if (!src_func->UseDefaultCompiler()) {
+        auto compiler = FunctionGetAttr(src_func, attr::kCompiler);
+        const tvm::ir::StringImm* code_gen = compiler.as<tvm::ir::StringImm>();
+        CHECK(code_gen) << "No external codegen is set";
+        if (ext_mods.find(code_gen->value) == ext_mods.end()) {
+          ext_mods[code_gen->value] = relay::ModuleNode::make({}, {});
+        }
+        auto ext_symbol = FunctionGetAttr(src_func, attr::kExternalSymbol);
+        const tvm::ir::StringImm* symbol_name = ext_symbol.as<tvm::ir::StringImm>();
+        CHECK(symbol_name) << "No external symbol is set for:\n" << AsText(src_func, false);
+        auto gv = GlobalVarNode::make(symbol_name->value);
+        ext_mods[code_gen->value]->Add(gv, src_func);
+        cached_ext_funcs.push_back(it.first);
+      }
+    }
+
+    Array<tvm::runtime::Module> ret;
+    for (const auto& it : ext_mods) {
+      std::string ext_name = "relay.ext." + it.first;
+      auto pf = tvm::runtime::Registry::Get(ext_name);
+      CHECK(pf) << "Failed to find the codegen tool for " << ext_name << "\n";
+      runtime::Module ext_mod = (*pf)(it.second);
+      CHECK(ext_mod.defined()) << "No external runtime is generated.";
+      ret.push_back(ext_mod);
+    }
+
+    // No need to cache external functions as we collected them all to create
+    // external runtime modules.
+    for (const auto& it : cached_ext_funcs) {
+      cache_.erase(it);
+    }
+    return ret;
+  }
+
   void Clear() final {
     cache_.clear();
   }
@@ -648,6 +689,18 @@ class CompileEngineImpl : public CompileEngineNode {
       value->use_count = 0;
       cache_[key] = value;
     }
+    // No need to lower external functions for now. We will invoke the external
+    // codegen tool once and lower all functions together.
+    if (!key->source_func->UseDefaultCompiler()) {
+      auto cache_node = make_node<CachedFuncNode>();
+      const auto name_node =
+          FunctionGetAttr(key->source_func, attr::kExternalSymbol).as<tvm::ir::StringImm>();
+      CHECK(name_node != nullptr) << "External function has not been attached a name yet.";
+      cache_node->func_name = name_node->value;
+      cache_node->target = tvm::target::ext_dev();
+      value->cached_func = CachedFunc(cache_node);
+      return value;
+    }
     // Enforce use the target.
     With<Target> target_scope(key->target);
 
@@ -759,42 +812,46 @@ const CompileEngine& CompileEngine::Global() {
   return *inst;
 }
 
-
 TVM_REGISTER_GLOBAL("relay.backend._make_CCacheKey")
 .set_body_typed<CCacheKey(Function, Target)>(CCacheKeyNode::make);
 
 TVM_REGISTER_GLOBAL("relay.backend._CompileEngineGlobal")
 .set_body_typed<CompileEngine()>([]() {
-    return CompileEngine::Global();
-  });
+  return CompileEngine::Global();
+});
 
 TVM_REGISTER_GLOBAL("relay.backend._CompileEngineClear")
 .set_body_typed<void(const CompileEngine&)>([](CompileEngine self) {
-    self->Clear();
-  });
+  self->Clear();
+});
 
 TVM_REGISTER_GLOBAL("relay.backend._CompileEngineLower")
 .set_body_typed<CachedFunc(CompileEngine, CCacheKey)>(
     [](CompileEngine self, CCacheKey key) {
-      return self->Lower(key);
-    });
+  return self->Lower(key);
+});
 
 TVM_REGISTER_GLOBAL("relay.backend._CompileEngineLowerShapeFunc")
 .set_body_typed<CachedFunc(CompileEngine, CCacheKey)>(
     [](CompileEngine self, CCacheKey key) {
-      return self->LowerShapeFunc(key);
-    });
+  return self->LowerShapeFunc(key);
+});
+
+TVM_REGISTER_GLOBAL("relay.backend._CompileLowerExternalFunctions")
+.set_body_typed<void(const CompileEngine&)>([](CompileEngine self) {
+  return self->LowerExternalFunctions();
+});
 
 TVM_REGISTER_GLOBAL("relay.backend._CompileEngineJIT")
 .set_body_typed<PackedFunc(CompileEngine, CCacheKey)>(
     [](CompileEngine self, CCacheKey key) {
-      return self->JIT(key);
-    });
+  return self->JIT(key);
+});
 
 TVM_REGISTER_GLOBAL("relay.backend._CompileEngineListItems")
 .set_body_typed<Array<NodeRef>(CompileEngine)>(
     [](CompileEngine self){
-      return static_cast<CompileEngineImpl*>(self.operator->())->ListItems();
-    });
+  return static_cast<CompileEngineImpl*>(self.operator->())->ListItems();
+});
 }  // namespace relay
 }  // namespace tvm
diff --git a/src/relay/backend/compile_engine.h b/src/relay/backend/compile_engine.h
index 31e246ecf1fe..596dfa7154f7 100644
--- a/src/relay/backend/compile_engine.h
+++ b/src/relay/backend/compile_engine.h
@@ -26,6 +26,7 @@
 #define TVM_RELAY_BACKEND_COMPILE_ENGINE_H_
 
 #include <tvm/lowered_func.h>
+#include <tvm/runtime/module.h>
 #include <tvm/relay/analysis.h>
 #include <tvm/relay/expr.h>
 #include <tvm/relay/transform.h>
@@ -186,6 +187,12 @@ class CompileEngineNode : public Node {
    * \return The result.
    */
   virtual CachedFunc LowerShapeFunc(const CCacheKey& key) = 0;
+  /*!
+   * \brief Lower the external function using external codegen tools.
+   * \return The runtime moduels for each needed external codegen tool.
+   */
+  virtual tvm::Array<tvm::runtime::Module> LowerExternalFunctions() = 0;
+
   /*! \brief clear the cache. */
   virtual void Clear() = 0;
 
diff --git a/src/relay/backend/contrib/codegen_c/codegen.cc b/src/relay/backend/contrib/codegen_c/codegen.cc
new file mode 100644
index 000000000000..4a4a60a33509
--- /dev/null
+++ b/src/relay/backend/contrib/codegen_c/codegen.cc
@@ -0,0 +1,226 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+#include <tvm/relay/expr_functor.h>
+#include <tvm/relay/transform.h>
+#include <tvm/relay/type.h>
+#include <tvm/runtime/module.h>
+#include <tvm/runtime/object.h>
+
+#include <fstream>
+#include <sstream>
+
+#include "codegen_c.h"
+
+namespace tvm {
+namespace relay {
+namespace contrib {
+
+/*!
+ * \brief An example codegen that is only used for quick prototyping and testing
+ * purpose. Only several binary options are covered. Users
+ * may need to extend them to cover more operators.
+ */
+class CodegenC : public ExprVisitor, public CodegenCBase {
+ public:
+  explicit CodegenC(const std::string& id) { this->ext_func_id_ = id; }
+
+  void VisitExpr_(const VarNode* node) {
+    ext_func_args_.push_back(node->name_hint());
+    out_.clear();
+    out_.push_back({node->name_hint(), 0});
+  }
+
+  void VisitExpr_(const CallNode* call) final {
+    std::ostringstream macro_stream;
+    std::ostringstream decl_stream;
+    std::ostringstream buf_stream;
+
+    std::string func_name = ext_func_id_ + "_" + std::to_string(func_idx++);
+
+    // Make function declaration
+    macro_stream << "CSOURCE_BINARY_OP_" << call->args.size() << "D(" << func_name << ", ";
+
+    if (IsOp(call, "add")) {
+      macro_stream << "+";
+    } else if (IsOp(call, "subtract")) {
+      macro_stream << "-";
+    } else if (IsOp(call, "multiply")) {
+      macro_stream << "*";
+    } else {
+      LOG(FATAL) << "Unrecognized op";
+    }
+
+    auto in_shape = GetShape(call->args[0]->checked_type());
+    for (size_t i = 0; i < in_shape.size(); ++i) {
+      macro_stream << ", " << in_shape[i];
+    }
+    macro_stream << ");";
+    func_decl_.push_back(macro_stream.str());
+
+    // Make function call when visiting arguments
+    bool first = true;
+    decl_stream << func_name << "(";
+    for (size_t i = 0; i < call->args.size(); ++i) {
+      VisitExpr(call->args[i]);
+      for (auto out : out_) {
+        if (!first) {
+          decl_stream << ", ";
+        }
+        first = false;
+        decl_stream << out.first;
+      }
+    }
+
+    auto type_node = call->checked_type().as<TensorTypeNode>();
+    CHECK(type_node != nullptr && runtime::TypeMatch(type_node->dtype, kDLFloat, 32))
+        << "Only support single output tensor with float type";
+    std::string out = "buf_" + std::to_string(buf_idx_++);
+    auto out_shape = GetShape(call->checked_type());
+    int out_size = 1;
+    for (size_t i = 0; i < out_shape.size(); ++i) {
+      out_size *= out_shape[i];
+    }
+    buf_stream << "float* " << out << " = (float*)std::malloc(4 * " << out_size << ");";
+    buf_decl_.push_back(buf_stream.str());
+
+    decl_stream << ", " << out << ");";
+    ext_func_body.push_back(decl_stream.str());
+
+    // Update output buffer
+    out_.clear();
+    out_.push_back({out, out_size});
+  }
+
+  /*!
+   * \brief Emit the source code that invokes C compiler compatible wrappers.
+   *
+   * \return The emitted code.
+   */
+  std::string JIT() {
+    // Write function macros
+    for (auto decl : func_decl_) {
+      code_stream_ << decl << "\n";
+    }
+    return JitImpl(ext_func_id_, ext_func_args_, buf_decl_, ext_func_body, out_);
+  }
+
+ private:
+  /*! \brief The function id that represents a C source function. */
+  std::string ext_func_id_ = "";
+  /*! \brief The index of a wrapped C function. */
+  int func_idx = 0;
+  /*! \brief The index of allocated buffers. */
+  int buf_idx_ = 0;
+  /*! \brief The arguments of a C compiler compatible function. */
+  std::vector<std::string> ext_func_args_;
+  /*! \brief The statements of a C compiler compatible function. */
+  std::vector<std::string> ext_func_body;
+  /*! \brief The declaration statements of a C compiler compatible function. */
+  std::vector<std::string> func_decl_;
+  /*! \brief The declaration statements of buffers. */
+  std::vector<std::string> buf_decl_;
+  /*! \brief The name and index pairs for output. */
+  std::vector<std::pair<std::string, int>> out_;
+};
+
+class CSourceCodegen : public CSourceModuleCodegenBase {
+ public:
+  void GenCFunc(const Function& func) {
+    CHECK(func.defined()) << "Input error: expect a Relay function.";
+
+    // Record the external symbol for runtime lookup.
+    auto sid = GetExtSymbol(func);
+
+    auto builder = CodegenC(sid);
+    builder.VisitExpr(func->body);
+    code_stream_ << builder.JIT();
+  }
+
+  runtime::Module CreateCSourceModule(const NodeRef& ref) override {
+    // Create headers
+    code_stream_ << "#include <cstdint>\n";
+    code_stream_ << "#include <iostream>\n";
+    code_stream_ << "#include <cstdlib>\n";
+    code_stream_ << "#include <stdio.h>\n";
+    code_stream_ << "#include <cstring>\n";
+    code_stream_ << "#include <tvm/runtime/c_runtime_api.h>\n";
+    code_stream_ << "#include <dlpack/dlpack.h>\n";
+
+    // Append some common macro for operator definition.
+    const char* operator_macro = R"op_macro(
+    #define CSOURCE_BINARY_OP_1D(p_ID_, p_OP_, p_DIM1_)       \
+      extern "C" void p_ID_(float* a, float* b, float* out) { \
+        for (int64_t i = 0; i < p_DIM1_; ++i) {               \
+          out[i] = a[i] p_OP_ b[i];                           \
+        }                                                     \
+      }
+    
+    #define CSOURCE_BINARY_OP_2D(p_ID_, p_OP_, p_DIM1_, p_DIM2_)  \
+      extern "C" void p_ID_(float* a, float* b, float* out) {     \
+        for (int64_t i = 0; i < p_DIM1_; ++i) {                   \
+          for (int64_t j = 0; j < p_DIM2_; ++j) {                 \
+            int64_t k = i * p_DIM2_ + j;                          \
+            out[k] = a[k] p_OP_ b[k];                             \
+          }                                                       \
+        }                                                         \
+      }
+    )op_macro";
+
+    code_stream_ << operator_macro << "\n\n";
+
+    if (ref->IsInstance<FunctionNode>()) {
+      GenCFunc(Downcast<Function>(ref));
+    } else if (ref->IsInstance<relay::ModuleNode>()) {
+      relay::Module mod = Downcast<relay::Module>(ref);
+      for (const auto& it : mod->functions) {
+        GenCFunc(Downcast<Function>(it.second));
+      }
+    } else {
+      LOG(FATAL) << "The input ref is expected to be a Relay function or module"
+                 << "\n";
+    }
+
+    // Create a CSourceModule
+    const auto* pf = runtime::Registry::Get("module.csource_module_create");
+    CHECK(pf != nullptr) << "Cannot find csource module to create the external runtime module";
+    return (*pf)(code_stream_.str(), "cc");
+  }
+
+ private:
+  std::ostringstream code_stream_;
+};
+
+/*!
+ * \brief The external compiler/codegen tool. It takes a Relay expression/module and
+ * compile it into a runtime module.
+ *
+ * The external codegen tool should have been registered similiarly to LLVM,
+ * CUDA, etc, under TVM, so the generated code could be packed in a runtime
+ * module. This module simplifies code serialization and invocation.
+ */
+runtime::Module CCompiler(const NodeRef& ref) {
+  CSourceCodegen csource;
+  return csource.CreateCSourceModule(ref);
+}
+
+TVM_REGISTER_API("relay.ext.ccompiler").set_body_typed(CCompiler);
+
+}  // namespace contrib
+}  // namespace relay
+}  // namespace tvm
diff --git a/src/relay/backend/contrib/codegen_c/codegen_c.h b/src/relay/backend/contrib/codegen_c/codegen_c.h
new file mode 100644
index 000000000000..1319ca2ff787
--- /dev/null
+++ b/src/relay/backend/contrib/codegen_c/codegen_c.h
@@ -0,0 +1,270 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * \file src/relay/backend/contrib/codegen_c/codegen_c.h
+ * \brief The base class for external codegen tools.
+ */
+#ifndef TVM_RELAY_BACKEND_CONTRIB_CODEGEN_C_CODEGEN_C_H_
+#define TVM_RELAY_BACKEND_CONTRIB_CODEGEN_C_CODEGEN_C_H_
+
+#include <tvm/relay/expr.h>
+#include <tvm/relay/op.h>
+#include <sstream>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace tvm {
+namespace relay {
+namespace contrib {
+
+class CSourceModuleCodegenBase {
+ public:
+  CSourceModuleCodegenBase() = default;
+
+  /*!
+   * \brief Create a runtime module for the external library. For example, it
+   * could be a CSourceModule that can be directly compiled and linked together
+   * with a DSOModule, or a json style module that emitts a json artifact that
+   * is able to be executed by a customized json runtime.
+   *
+   * \param ref The ext_func Relay expression/module to be executed using extern ops.
+   *
+   * \return A runtime module.
+   */
+  virtual runtime::Module CreateCSourceModule(const NodeRef& ref) = 0;
+
+  /*!
+   * \brief Get the external symbol of the Relay function name.
+   *
+   * \param func The provided function.
+   *
+   * \return An external symbol.
+   */
+  std::string GetExtSymbol(const Function& func) const {
+    const auto name_node = FunctionGetAttr(func, attr::kExternalSymbol).as<tvm::ir::StringImm>();
+    CHECK(name_node != nullptr) << "Fail to retrieve external symbol.";
+    std::string ext_symbol = name_node->value;
+    return ext_symbol;
+  }
+};
+
+// The base class to generate the declaration functions in C.
+class CodegenCBase {
+ protected:
+  /*! \brief Print indents using spaces. */
+  void PrintIndents() {
+    for (int i = 0; i < indent_; i++) {
+      code_stream_ << ' ';
+    }
+  }
+
+  /*!
+   * \brief Enter a new scope.
+   */
+  void EnterScope() { indent_ += 2; }
+
+  /*!
+   * \brief Exit a scope.
+   */
+  void ExitScope() {
+    CHECK_GE(indent_, 2U) << "Wrong ident found.";
+    indent_ -= 2;
+  }
+
+  /*!
+   * \brief Gerenate C code for the external function.
+   *
+   * \param func_name The name of the external function.
+   * \param arg_cnt The expected number of arguments.
+   *
+   * \code
+   *
+   * // An example code for the generated C function.
+   * extern "C" void foo(TVMValue* value, int* type_code, int nargs) {
+   *   if (nargs != 3) {
+   *     printf("foo expects 3 args, but received %d\n", nargs);
+   *     return 1;
+   *   }
+   *
+   *   DLTensor* arg0 = static_cast<DLTensor*>(value[0].v_handle);
+   *   DLTensor* arg1 = static_cast<DLTensor*>(value[1].v_handle);
+   *   DLTensor* out = static_cast<DLTensor*>(value[2].v_handle);
+   *
+   *   foo_(static_cast<float*>(arg0->data),
+   *        static_cast<float*>(arg1->data),
+   *        static_cast<float*>(out->data));
+   *   return 0;
+   * }
+   *
+   * \endcode
+   */
+  void GenerateBackendCFunc(const std::string& func_name, int arg_cnt) {
+    // Print signature
+    code_stream_ << "\n";
+    code_stream_ << "extern \"C\" int " << func_name;
+    code_stream_ << "(TVMValue* value, int* type_code, int nargs) {\n";
+    EnterScope();
+    // Print guard
+    PrintIndents();
+    code_stream_ << "if (nargs != " << arg_cnt << "){\n";
+    EnterScope();
+    PrintIndents();
+    code_stream_ << "printf(\"" << func_name << " expects " << arg_cnt
+                 << " arguments, but received %d\\n\", nargs);\n";
+    PrintIndents();
+    code_stream_ << "return 1;\n";
+    ExitScope();
+    PrintIndents();
+    code_stream_ << "}\n";
+
+    // According to TVM's calling convention, the last one is output.
+    for (int i = 0; i < arg_cnt; i++) {
+      PrintIndents();
+      code_stream_ << "DLTensor* arg" << i << " = "
+                   << "static_cast<DLTensor*>(value[" << i << "].v_handle);\n";
+    }
+    // Generate the call.
+    PrintIndents();
+    code_stream_ << func_name << "_(";
+    for (int i = 0; i < arg_cnt - 1; i++) {
+      code_stream_ << "static_cast<float*>(arg" << i << "->data), ";
+    }
+    if (arg_cnt > 0) {
+      code_stream_ << "static_cast<float*>(arg" << arg_cnt - 1 << "->data)";
+    }
+    code_stream_ << ");\n\n";
+    PrintIndents();
+    code_stream_ << "return 0;\n";
+    ExitScope();
+    code_stream_ << "}";
+  }
+
+  /*!
+   * \brief Emit the code for external runtime.
+   *
+   * \return The code string.
+   */
+  virtual std::string JIT() = 0;
+
+  /*!
+   * \brief Extract the shape from a Relay tensor type.
+   *
+   * \param type The provided type.
+   *
+   * \return The extracted shape in a list.
+   */
+  std::vector<int> GetShape(const Type& type) const {
+    const auto* ttype = type.as<TensorTypeNode>();
+    CHECK(ttype) << "Expect TensorTypeNode";
+    std::vector<int> shape;
+    for (size_t i = 0; i < ttype->shape.size(); ++i) {
+      auto* val = ttype->shape[i].as<IntImm>();
+      CHECK(val);
+      shape.push_back(val->value);
+    }
+    return shape;
+  }
+
+  /*!
+   * \brief Check if a call has the provided name.
+   *
+   * \param call A Relay call node.
+   * \param op_name The name of the expected call.
+   *
+   * \return true if the call's name is equivalent to the given name. Otherwise,
+   * false.
+   */
+  bool IsOp(const CallNode* call, std::string op_name) const {
+    const auto* op_node = call->op.as<OpNode>();
+    CHECK(op_node) << "Expects a single op.";
+    Op op = GetRef<Op>(op_node);
+    return op == Op::Get(op_name);
+  }
+
+  /*!
+   * \brief A common interface that is used by various external runtime to
+   * generate the wrapper to invoke external kernels.
+   *
+   * \param ext_func_id The unique id of an external function. It will be used
+   * during runtime to pick the correct external function.
+   * \param args The arguments used by the external function.
+   * \param buf_decl The declaration of temporary buffers that used to store the
+   * intermeidate of each external kernel.
+   * \param body The statements of the external function.
+   * \param out The name and id pairs for output.
+   *
+   * \return The emitted code string.
+   */
+  std::string JitImpl(std::string ext_func_id, std::vector<std::string> args,
+                      std::vector<std::string> buf_decl, std::vector<std::string> body,
+                      std::vector<std::pair<std::string, int>> out) {
+    // Create the signature. For example, it could be:
+    // extern "C" void dnnl_0_(float* input0, float* input1, float* out, int M, int N) {}
+    code_stream_ << "extern \"C\" void " << ext_func_id << "_(";
+
+    for (const auto& arg : args) {
+      code_stream_ << "float* " << arg << ", ";
+    }
+    code_stream_ << "float* out) {\n";
+    this->EnterScope();
+
+    // Function body
+    for (auto decl : buf_decl) {
+      this->PrintIndents();
+      code_stream_ << decl << "\n";
+    }
+    code_stream_ << "\n";
+    for (auto stmt : body) {
+      this->PrintIndents();
+      code_stream_ << stmt << "\n";
+    }
+
+    // Copy output
+    CHECK_EQ(out.size(), 1U) << "Internal error: only single output is support.";
+    this->PrintIndents();
+    code_stream_ << "std::memcpy(out, " << out[0].first << ", 4 * " << out[0].second << ");\n";
+
+    // Free buffers
+    for (size_t i = 0; i < buf_decl.size(); i++) {
+      this->PrintIndents();
+      code_stream_ << "std::free(buf_" << i << ");\n";
+    }
+
+    this->ExitScope();
+    code_stream_ << "}\n";
+
+    // Create the wrapper to call the ext_func
+    this->GenerateBackendCFunc(ext_func_id, args.size() + 1 /* output */);
+    return code_stream_.str();
+  }
+
+  /*! \brief The external function source code stream. */
+  std::ostringstream code_stream_;
+
+ private:
+  /*! \brief Indent of the source code. */
+  int indent_{0};
+};
+
+}  // namespace contrib
+}  // namespace relay
+}  // namespace tvm
+#endif  // TVM_RELAY_BACKEND_CONTRIB_CODEGEN_C_CODEGEN_C_H_
diff --git a/src/relay/backend/contrib/dnnl/codegen.cc b/src/relay/backend/contrib/dnnl/codegen.cc
new file mode 100644
index 000000000000..5c68d5a1711e
--- /dev/null
+++ b/src/relay/backend/contrib/dnnl/codegen.cc
@@ -0,0 +1,310 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * \file src/relay/backend/contrib/dnnl/codegen.cc
+ * \brief Implementation of DNNL codegen APIs.
+ */
+
+#include <tvm/relay/attrs/nn.h>
+#include <tvm/relay/expr_functor.h>
+#include <tvm/relay/transform.h>
+#include <tvm/relay/type.h>
+#include <tvm/runtime/module.h>
+#include <tvm/runtime/registry.h>
+
+#include <fstream>
+#include <sstream>
+
+#include "../codegen_c/codegen_c.h"
+
+namespace tvm {
+namespace relay {
+namespace contrib {
+
+// TODO(@zhiics, @comaniac): This is a basic implementation. We should implement
+// all utilities and make a base class for users to implement.
+class CodegenDNNL : public ExprVisitor, public CodegenCBase {
+ public:
+  explicit CodegenDNNL(const std::string& id) { this->ext_func_id_ = id; }
+
+  void VisitExpr_(const VarNode* node) final {
+    ext_func_args_.push_back(node->name_hint());
+    out_.clear();
+    out_.push_back({node->name_hint(), 0});
+  }
+
+  void VisitExpr_(const TupleGetItemNode* op) final {
+    // Do nothing
+  }
+
+  void VisitExpr_(const CallNode* call) final {
+    std::ostringstream decl_stream;
+    std::ostringstream buf_stream;
+    // Args: ID
+    std::vector<std::string> args;
+
+    // Get the arguments for various DNNL kernels.
+    if (IsOp(call, "nn.conv2d")) {
+      decl_stream << "dnnl_conv2d";
+      args = Conv2d(call);
+    } else if (IsOp(call, "nn.dense")) {
+      decl_stream << "dnnl_dense";
+      args = Dense(call);
+    } else if (IsOp(call, "nn.relu")) {
+      decl_stream << "dnnl_relu";
+      args = Relu(call);
+    } else if (IsOp(call, "nn.batch_norm")) {
+      decl_stream << "dnnl_bn";
+      args = BatchNorm(call);
+    } else if (IsOp(call, "add")) {
+      decl_stream << "dnnl_add";
+      args = Add(call);
+    } else {
+      LOG(FATAL) << "Unsupported op: " << AsText(call->op, false);
+    }
+
+    // Make function call with input buffers when visiting arguments
+    bool first = true;
+    decl_stream << "(";
+    for (size_t i = 0; i < call->args.size(); ++i) {
+      VisitExpr(call->args[i]);
+      for (auto out : out_) {
+        if (!first) {
+          decl_stream << ", ";
+        }
+        first = false;
+        decl_stream << out.first;
+      }
+    }
+
+    // Analyze the output buffer
+    auto type_node = call->checked_type().as<TensorTypeNode>();
+    CHECK(type_node != nullptr && runtime::TypeMatch(type_node->dtype, kDLFloat, 32))
+        << "Only support single output tensor with float type";
+    std::string out = "buf_" + std::to_string(buf_idx_++);
+    auto out_shape = GetShape(call->checked_type());
+    int out_size = 1;
+    for (size_t i = 0; i < out_shape.size(); ++i) {
+      out_size *= out_shape[i];
+    }
+    this->PrintIndents();
+    buf_stream << "float* " << out << " = (float*)std::malloc(4 * " << out_size << ");";
+    buf_decl_.push_back(buf_stream.str());
+    decl_stream << ", " << out;
+
+    // Attach attribute arguments
+    for (size_t i = 0; i < args.size(); ++i) {
+      decl_stream << ", " << args[i];
+    }
+    decl_stream << ");";
+    ext_func_body.push_back(decl_stream.str());
+
+    // Update output buffer
+    out_.clear();
+    out_.push_back({out, out_size});
+  }
+
+  std::string JIT(void) {
+    return JitImpl(ext_func_id_, ext_func_args_, buf_decl_, ext_func_body, out_);
+  }
+
+ private:
+  std::vector<std::string> Conv2d(const CallNode* call) {
+    std::vector<std::string> args;
+    const auto* conv2d_attr = call->attrs.as<Conv2DAttrs>();
+    CHECK(conv2d_attr);
+
+    auto ishape = GetShape(call->args[0]->checked_type());
+    auto wshape = GetShape(call->args[1]->checked_type());
+
+    // Args: N, C, H, W
+    for (auto s : ishape) {
+      args.push_back(std::to_string(s));
+    }
+
+    // Args: O, G, Ph, Pw, Kh, Kw, Sh, Sw
+    args.push_back(std::to_string(wshape[0]));
+    args.push_back(std::to_string(conv2d_attr->groups));
+    args.push_back(std::to_string(conv2d_attr->padding[0].as<IntImm>()->value));
+    args.push_back(std::to_string(conv2d_attr->padding[1].as<IntImm>()->value));
+    args.push_back(std::to_string(wshape[2]));
+    args.push_back(std::to_string(wshape[3]));
+    args.push_back(std::to_string(conv2d_attr->strides[0].as<IntImm>()->value));
+    args.push_back(std::to_string(conv2d_attr->strides[1].as<IntImm>()->value));
+
+    return args;
+  }
+
+  std::vector<std::string> Dense(const CallNode* call) {
+    std::vector<std::string> args;
+    auto ishape = GetShape(call->args[0]->checked_type());
+    auto wshape = GetShape(call->args[1]->checked_type());
+
+    // Args: N, C, O
+    args.push_back(std::to_string(ishape[0]));
+    args.push_back(std::to_string(ishape[1]));
+    args.push_back(std::to_string(wshape[0]));
+
+    return args;
+  }
+
+  std::vector<std::string> Relu(const CallNode* call) {
+    std::vector<std::string> args;
+    auto ishape = GetShape(call->args[0]->checked_type());
+
+    // Args: N, C, H, W
+    for (auto s : ishape) {
+      args.push_back(std::to_string(s));
+    }
+
+    return args;
+  }
+
+  std::vector<std::string> BatchNorm(const CallNode* call) {
+    std::vector<std::string> args;
+    const auto* bn_attr = call->attrs.as<BatchNormAttrs>();
+    auto ishape = GetShape(call->args[0]->checked_type());
+
+    // Args: N, C, H, W
+    for (auto s : ishape) {
+      args.push_back(std::to_string(s));
+    }
+
+    // Args: epsilon
+    args.push_back(std::to_string(bn_attr->epsilon));
+
+    return args;
+  }
+
+  std::vector<std::string> Add(const CallNode* call) {
+    std::vector<std::string> args;
+    auto ishape = GetShape(call->args[0]->checked_type());
+
+    // Args: H, W
+    for (auto s : ishape) {
+      args.push_back(std::to_string(s));
+    }
+
+    return args;
+  }
+
+  /*! \brief The id of the external dnnl ext_func. */
+  std::string ext_func_id_{""};
+  /*!
+   * \brief The index to track the output buffer. Each kernel will redirect the
+   * output to a buffer that may be consumed by other kernels.
+   */
+  int buf_idx_{0};
+  /*! \brief The arguments used by a wrapped function that calls DNNL kernels. */
+  std::vector<std::string> ext_func_args_;
+  /*! \brief statement of the function that will be compiled using DNNL kernels. */
+  std::vector<std::string> ext_func_body;
+  /*! \brief The declaration of intermeidate buffers. */
+  std::vector<std::string> buf_decl_;
+  /*! \brief The name of the the outputs. */
+  std::vector<std::pair<std::string, int>> out_;
+};
+
+/*!
+ * \brief The DNNL codegen helper to generate wrapepr function calls of DNNL
+ * libraries. The code is a CSourceModule that can be compiled separately and
+ * linked together with a DSOModule.
+ */
+class DNNLModuleCodegen : public CSourceModuleCodegenBase {
+ public:
+  // Create a corresponding DNNL function for the given relay Function.
+  void GenDNNLFunc(const Function& func) {
+    CHECK(func.defined()) << "Input error: expect a Relay function.";
+    const auto* call = func->body.as<CallNode>();
+    CHECK(call) << "DNNL expects a single convolution or dense op";
+
+    // Record the external symbol for runtime lookup.
+    auto sid = GetExtSymbol(func);
+
+    auto builder = CodegenDNNL(sid);
+    builder.VisitExpr(func->body);
+    code_stream_ << builder.JIT();
+  }
+
+  /*!
+   * \brief The overridden function that will create a CSourceModule. In order
+   * to compile the generated C source code, users need to specify the paths to
+   * some libraries, including some TVM required and dnnl specific ones. To make
+   * linking simpiler, the DNNL kernels are wrapped in a TVM compatible manner
+   * and live under tvm/src/runtime/contrib/dnnl folder.
+   *
+   * \param ref An object ref that could be either a Relay function or module.
+   *
+   * \return The runtime module that contains C source code.
+   */
+  runtime::Module CreateCSourceModule(const NodeRef& ref) override {
+    // Create headers
+    code_stream_ << "#include <cstdint>\n";
+    code_stream_ << "#include <cstdlib>\n";
+    code_stream_ << "#include <cstring>\n";
+    code_stream_ << "#include <tvm/runtime/c_runtime_api.h>\n";
+    code_stream_ << "#include <dlpack/dlpack.h>\n";
+    // dnnl_kernel file is saved under src/runtime/contrib/dnnl so that we don't
+    // expose it to ordinary users. To make export_library use it, users need to
+    // pass -I${PATH_TO_TVM}/src/runtime/contrib
+    code_stream_ << "#include <dnnl/dnnl_kernel.h>\n";
+    code_stream_ << "using namespace tvm::runtime::contrib;\n";
+    code_stream_ << "\n";
+
+    if (ref->IsInstance<FunctionNode>()) {
+      GenDNNLFunc(Downcast<Function>(ref));
+    } else if (ref->IsInstance<relay::ModuleNode>()) {
+      relay::Module mod = Downcast<relay::Module>(ref);
+      for (const auto& it : mod->functions) {
+        GenDNNLFunc(Downcast<Function>(it.second));
+      }
+    } else {
+      LOG(FATAL) << "The input ref is expected to be a Relay function or module"
+                 << "\n";
+    }
+
+    // Create a CSourceModule
+    const auto* pf = runtime::Registry::Get("module.csource_module_create");
+    CHECK(pf != nullptr) << "Cannot find csource module to create the external runtime module";
+    return (*pf)(code_stream_.str(), "cc");
+  }
+
+ private:
+  /*!
+   * \brief The code stream that prints the code that will be compiled using
+   * external codegen tools.
+   */
+  std::ostringstream code_stream_;
+};
+
+/*!
+ * \brief The external compiler/codegen tool. It takes a Relay expression/module and
+ * compile it into a runtime module.
+ */
+runtime::Module DNNLCompiler(const NodeRef& ref) {
+  DNNLModuleCodegen dnnl;
+  return dnnl.CreateCSourceModule(ref);
+}
+
+TVM_REGISTER_API("relay.ext.dnnl").set_body_typed(DNNLCompiler);
+
+}  // namespace contrib
+}  // namespace relay
+}  // namespace tvm
diff --git a/src/relay/backend/graph_runtime_codegen.cc b/src/relay/backend/graph_runtime_codegen.cc
index e2881785766c..fc12cf66900f 100644
--- a/src/relay/backend/graph_runtime_codegen.cc
+++ b/src/relay/backend/graph_runtime_codegen.cc
@@ -24,6 +24,7 @@
 
 #include <dmlc/any.h>
 #include <dmlc/json.h>
+#include <tvm/relay/module.h>
 #include <tvm/relay/expr_functor.h>
 #include <tvm/runtime/device_api.h>
 
@@ -55,6 +56,7 @@ using TargetsMap = std::unordered_map<int, Target>;
 struct LoweredOutput {
   std::string graph_json;
   Map<std::string, Array<LoweredFunc> > lowered_funcs;
+  Array<tvm::runtime::Module> external_mods;
   std::unordered_map<std::string, tvm::runtime::NDArray> params;
 };
 
@@ -226,6 +228,7 @@ class GraphRuntimeCodegen
       }
       ret.lowered_funcs.Set(kv.first, tmp);
     }
+    ret.external_mods = compile_engine_->LowerExternalFunctions();
     return ret;
   }
 
@@ -380,6 +383,25 @@ class GraphRuntimeCodegen
     }
     return fields;
   }
+
+  std::vector<GraphNodeRef> GraphAddCallNode(const CallNode* op,
+                                             const std::string& op_name,
+                                             const std::string& func_name) {
+    std::vector<GraphNodeRef> inputs;
+    for (auto arg : op->args) {
+      auto res = VisitExpr(arg);
+      for (auto nr : res) {
+        inputs.push_back(nr);
+      }
+    }
+    auto node = GraphOpNode::make_node_ptr(op_name,
+                                           GraphAttrs(),
+                                           func_name,
+                                           inputs,
+                                           GraphAttrs());
+    return AddNode(node, GetRef<Expr>(op));
+  }
+
   std::vector<GraphNodeRef> VisitExpr_(const CallNode* op) override {
     Expr expr = GetRef<Expr>(op);
     Function func;
@@ -398,17 +420,26 @@ class GraphRuntimeCodegen
                  << "(i.e functions composed of fusable operator invocations)";
     }
 
-    CHECK_GE(storage_device_map_.count(expr), 0);
     auto pf0 = GetPackedFunc("relay.backend._make_CCacheKey");
     auto pf1 = GetPackedFunc("relay.backend._CompileEngineLower");
+    Target target;
+    // Handle external function
+    if (!func->UseDefaultCompiler()) {
+      target = tvm::target::ext_dev();
+      CCacheKey key = (*pf0)(func, target);
+      CachedFunc ext_func = (*pf1)(compile_engine_, key);
+      CHECK(ext_func.defined()) << "External function is not defined.";
+      return GraphAddCallNode(op, ext_func->func_name, ext_func->func_name);
+    }
+
+    CHECK_GE(storage_device_map_.count(expr), 0);
     auto &device_type = storage_device_map_[expr][1];
     auto call_dev_type = device_type[0]->value;
-    Target target;
+    // Normal Relay Function
     if (targets_.size() == 1) {
        // homogeneous execution.
-       for (auto kv : targets_) {
-         target = kv.second;
-       }
+      const auto& it = targets_.begin();
+      target = (*it).second;
     } else {
       // heterogeneous execution.
       std::string call_dev_name;
@@ -424,28 +455,17 @@ class GraphRuntimeCodegen
       target = targets_[call_dev_type];
     }
     CCacheKey key = (*pf0)(func, target);
-    CachedFunc lowerd_func = (*pf1)(compile_engine_, key);
+    CachedFunc lowered_func = (*pf1)(compile_engine_, key);
     if (!lowered_funcs_.count(target->str())) {
       lowered_funcs_[target->str()] = {};
     }
-    for (auto f : lowerd_func->funcs) {
+    for (auto f : lowered_func->funcs) {
       lowered_funcs_[target->str()].insert(f);
     }
 
-    std::vector<GraphNodeRef> inputs;
-    for (auto arg : op->args) {
-      auto res = VisitExpr(arg);
-      for (auto nr : res) {
-        inputs.push_back(nr);
-      }
-    }
-    auto& op_name = lowerd_func->func_name;
-    auto node = GraphOpNode::make_node_ptr(_GetUniqueName(op_name),
-                                           GraphAttrs(),
-                                           op_name,
-                                           inputs,
-                                           GraphAttrs());
-    return AddNode(node, expr);
+    return GraphAddCallNode(op,
+                           _GetUniqueName(lowered_func->func_name),
+                           lowered_func->func_name);
   }
 
   std::vector<GraphNodeRef> VisitExpr_(const LetNode* op) override {
@@ -470,7 +490,7 @@ class GraphRuntimeCodegen
     return {};
   }
   std::vector<GraphNodeRef> VisitExpr_(const FunctionNode* op) override {
-    throw std::invalid_argument("function not supported");
+    CHECK(!op->UseDefaultCompiler()) << "Only functions supported by custom codegen";
     return {};
   }
   std::vector<GraphNodeRef> VisitExpr_(const RefCreateNode* op) override {
@@ -628,7 +648,6 @@ class GraphRuntimeCodegenModule : public runtime::ModuleNode {
         }
         *rv = ret;
       });
-
     } else if (name == "get_param_by_name") {
       return PackedFunc([sptr_to_self, this](TVMArgs args, TVMRetValue* rv) {
         std::string key = args[0];
@@ -639,6 +658,10 @@ class GraphRuntimeCodegenModule : public runtime::ModuleNode {
       return PackedFunc([sptr_to_self, this](TVMArgs args, TVMRetValue* rv) {
         *rv = this->output_.lowered_funcs;
       });
+    } else if (name == "get_external_modules") {
+      return PackedFunc([sptr_to_self, this](TVMArgs args, TVMRetValue* rv) {
+        *rv = this->output_.external_mods;
+      });
     } else {
       return PackedFunc([](TVMArgs args, TVMRetValue* rv) {});
     }
diff --git a/src/relay/backend/vm/lambda_lift.cc b/src/relay/backend/vm/lambda_lift.cc
index b8250fd0dfb9..ab9dc8cbec63 100644
--- a/src/relay/backend/vm/lambda_lift.cc
+++ b/src/relay/backend/vm/lambda_lift.cc
@@ -37,21 +37,19 @@ namespace tvm {
 namespace relay {
 namespace vm {
 
-static const char* kIsClosure = "IsClosure";
-
 inline std::string GenerateName(const Function& func) {
   size_t hash = StructuralHash()(func);
   return std::string("lifted_name") + std::to_string(hash);
 }
 
 bool IsClosure(const Function& func) {
-  NodeRef res = FunctionGetAttr(func, kIsClosure);
+  NodeRef res = FunctionGetAttr(func, attr::kClosure);
   const ir::IntImm* pval = res.as<ir::IntImm>();
   return pval && pval->value != 0;
 }
 
 Function MarkClosure(const Function& func) {
-  return FunctionSetAttr(func, kIsClosure, tvm::Integer(1));
+  return FunctionSetAttr(func, attr::kClosure, tvm::Integer(1));
 }
 
 /* The goal of this class is to lift out any nested functions into top-level
diff --git a/src/relay/ir/expr.cc b/src/relay/ir/expr.cc
index 47e735f20fc8..c9619d95d681 100644
--- a/src/relay/ir/expr.cc
+++ b/src/relay/ir/expr.cc
@@ -157,13 +157,13 @@ FuncType FunctionNode::func_type_annotation() const {
 }
 
 bool FunctionNode::IsPrimitive() const {
-  NodeRef res = FunctionGetAttr(GetRef<Function>(this), "Primitive");
+  NodeRef res = FunctionGetAttr(GetRef<Function>(this), attr::kPrimitive);
   const ir::IntImm* pval = res.as<ir::IntImm>();
   return pval && pval->value != 0;
 }
 
 Function FunctionNode::SetParams(const tvm::Map<Var, Constant>& parameters) const {
-  return FunctionSetAttr(GetRef<Function>(this), "__params__", parameters);
+  return FunctionSetAttr(GetRef<Function>(this), attr::kParams, parameters);
 }
 
 TVM_REGISTER_API("relay._expr.FunctionSetParams")
@@ -173,7 +173,7 @@ TVM_REGISTER_API("relay._expr.FunctionSetParams")
 });
 
 tvm::Map<Var, Constant> FunctionNode::GetParams() const {
-  auto node_ref = FunctionGetAttr(GetRef<Function>(this), "__params__");
+  auto node_ref = FunctionGetAttr(GetRef<Function>(this), attr::kParams);
   return Downcast<tvm::Map<Var, Constant>>(node_ref);
 }
 
@@ -182,6 +182,12 @@ TVM_REGISTER_API("relay._expr.FunctionGetParams")
   return func->GetParams();
 });
 
+bool FunctionNode::UseDefaultCompiler() const {
+  NodeRef res = FunctionGetAttr(GetRef<Function>(this), attr::kCompiler);
+  const ir::StringImm* pval = res.as<ir::StringImm>();
+  return pval == nullptr || pval->value == "default";
+}
+
 NodeRef FunctionGetAttr(const Function& func, const std::string& key) {
   if (!func->attrs.defined()) { return NodeRef(); }
 
diff --git a/src/relay/pass/fuse_ops.cc b/src/relay/pass/fuse_ops.cc
index 904d24657cad..9aba1aca9a5b 100644
--- a/src/relay/pass/fuse_ops.cc
+++ b/src/relay/pass/fuse_ops.cc
@@ -239,7 +239,8 @@ class IndexedForwardGraph::Creator : private ExprVisitor {
     // Finally if the operator position is not a call node we will
     // need to call Update, as it may be an arbitrary expression.
     OpPatternKind op_pattern = kOpaque;
-    if (const OpNode* opnode = call->op.as<OpNode>()) {
+    const OpNode* opnode = call->op.as<OpNode>();
+    if (opnode != nullptr && call->op != Op::Get("nn.batch_norm")) {
       op_pattern = static_cast<OpPatternKind>(fpattern[GetRef<Op>(opnode)]);
     } else {
       this->Update(call->op, node, kOpaque);
@@ -932,7 +933,7 @@ class FuseMutator : private ExprMutator {
     visitor(body);
     const GroupInfo& ginfo = ginfo_[group];
     auto func = FunctionNode::make(ginfo.params, body, ret_type, {});
-    func = FunctionSetAttr(func, "Primitive", tvm::Integer(visitor.has_call));
+    func = FunctionSetAttr(func, attr::kPrimitive, tvm::Integer(visitor.has_call));
     return CallNode::make(func, ginfo.arguments, Attrs());
   }
 
diff --git a/src/relay/pass/pass_manager.cc b/src/relay/pass/pass_manager.cc
index b025d3787f9e..97b8fd681cb8 100644
--- a/src/relay/pass/pass_manager.cc
+++ b/src/relay/pass/pass_manager.cc
@@ -329,12 +329,10 @@ Module FunctionPassNode::operator()(const Module& mod,
   return updated_mod;
 }
 
-// TODO(zhiics) Create an enum attribute for FunctionNode
-// enum Attribute {kPrimitive, kSkipOptimization}
 bool FunctionPassNode::SkipFunction(const Function& func) const {
-  NodeRef res = FunctionGetAttr(func, "SkipOptimization");
-  const ir::IntImm* pval = res.as<ir::IntImm>();
-  return pval && pval->value != 0;
+  NodeRef skip_opt = FunctionGetAttr(func, attr::kSkipOptimization);
+  const ir::IntImm* pval = skip_opt.as<ir::IntImm>();
+  return (pval && pval->value != 0) || (!func->UseDefaultCompiler());
 }
 
 Sequential::Sequential(tvm::Array<Pass> passes, PassInfo pass_info) {
diff --git a/src/runtime/contrib/dnnl/dnnl.cc b/src/runtime/contrib/dnnl/dnnl.cc
new file mode 100644
index 000000000000..cc430b2c7c76
--- /dev/null
+++ b/src/runtime/contrib/dnnl/dnnl.cc
@@ -0,0 +1,247 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * \file src/runtime/contrib/dnnl/dnnl.cc
+ * \brief TVM compatible wrappers for dnnl kernels.
+ */
+
+#include "dnnl_kernel.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <algorithm>
+#include <iostream>
+#include <numeric>
+#include <string>
+#include <vector>
+
+namespace tvm {
+namespace runtime {
+namespace contrib {
+
+using namespace dnnl;
+
+typedef struct {
+  void** data;
+} DnnlPackedArgs;
+
+// Read from memory, write to handle
+inline void read_from_dnnl_memory(void* handle, const memory& mem) {
+  size_t bytes = mem.get_desc().get_size();
+
+  uint8_t* src = static_cast<uint8_t*>(mem.get_data_handle());
+  std::copy(src, src + bytes, reinterpret_cast<uint8_t*>(handle));
+}
+
+extern "C" void dnnl_conv2d(float* data, float* weights, float* out, int p_N_,
+                            int p_C_, int p_H_, int p_W_, int p_O_, int p_G_,
+                            int p_Ph_, int p_Pw_, int p_Kh_, int p_Kw_,
+                            int p_Sh_, int p_Sw_) {
+  using tag = memory::format_tag;
+  using dt = memory::data_type;
+  engine eng(engine::kind::cpu, 0);
+  stream s(eng);
+
+  memory::dims conv2d_src_tz = {p_N_, p_C_, p_H_, p_W_};
+  memory::dims conv2d_weights_tz = {p_O_, p_C_, p_Kh_, p_Kw_};
+  if (p_G_ > 1) conv2d_weights_tz = {p_G_, 1, p_C_ / p_G_, p_Kh_, p_Kw_};
+  memory::dims conv2d_bias_tz = {p_O_};
+  memory::dims conv2d_dst_tz = {p_N_, p_O_,
+                                (p_H_ - p_Kh_ + 2 * p_Ph_ + p_Sh_) / p_Sh_,
+                                (p_W_ - p_Kw_ + 2 * p_Pw_ + p_Sw_) / p_Sw_};
+  memory::dims conv2d_strides = {p_Sh_, p_Sw_};
+  memory::dims conv2d_padding = {p_Ph_, p_Pw_};
+
+  std::vector<float> conv2d_bias(p_O_, 0);
+
+  auto user_src_memory =
+      memory({{conv2d_src_tz}, dt::f32, tag::nchw}, eng, data);
+  auto user_weights_memory = memory(
+      {{conv2d_weights_tz}, dt::f32, (p_G_ > 1) ? tag::goihw : tag::oihw}, eng,
+      weights);
+  auto conv2d_user_bias_memory =
+      memory({{conv2d_bias_tz}, dt::f32, tag::x}, eng, conv2d_bias.data());
+
+  auto conv2d_src_md = memory::desc({conv2d_src_tz}, dt::f32, tag::any);
+  auto conv2d_bias_md = memory::desc({conv2d_bias_tz}, dt::f32, tag::any);
+  auto conv2d_weights_md = memory::desc({conv2d_weights_tz}, dt::f32, tag::any);
+  auto conv2d_dst_md = memory::desc({conv2d_dst_tz}, dt::f32, tag::nchw);
+
+  auto conv2d_desc = convolution_forward::desc(
+      prop_kind::forward_inference, algorithm::convolution_direct,
+      conv2d_src_md, conv2d_weights_md, conv2d_bias_md, conv2d_dst_md,
+      conv2d_strides, conv2d_padding, conv2d_padding);
+  auto conv2d_prim_desc = convolution_forward::primitive_desc(conv2d_desc, eng);
+
+  auto conv2d_src_memory = user_src_memory;
+  auto conv2d_weights_memory = user_weights_memory;
+  auto conv2d_dst_memory = memory(conv2d_prim_desc.dst_desc(), eng);
+
+  auto conv = convolution_forward(conv2d_prim_desc);
+  conv.execute(s, {{DNNL_ARG_SRC, conv2d_src_memory},
+                   {DNNL_ARG_WEIGHTS, conv2d_weights_memory},
+                   {DNNL_ARG_BIAS, conv2d_user_bias_memory},
+                   {DNNL_ARG_DST, conv2d_dst_memory}});
+  s.wait();
+  read_from_dnnl_memory(out, conv2d_dst_memory);
+}
+
+extern "C" void dnnl_dense(float* data, float* weight, float* out, int p_B_,
+                           int p_I_, int p_O_) {
+  using tag = memory::format_tag;
+  using dt = memory::data_type;
+
+  engine eng(engine::kind::cpu, 0);
+  stream s(eng);
+
+  memory::dims data_tz = {p_B_, p_I_};
+  memory::dims weight_tz = {p_O_, p_I_};
+  memory::dims bias_tz = {p_O_};
+  memory::dims dst_tz = {p_B_, p_O_};
+
+  auto data_md = memory::desc{{data_tz}, dt::f32, tag::nc};
+  auto weight_md = memory::desc({{weight_tz}, dt::f32, tag::nc});
+  auto bias_md = memory::desc({{bias_tz}, dt::f32, tag::x});
+  auto dst_md = memory::desc({{dst_tz}, dt::f32, tag::nc});
+
+  std::vector<float> bias(p_O_, 0);
+  auto data_memory = memory(data_md, eng, data);
+  auto weight_memory = memory(weight_md, eng, weight);
+  auto bias_memory = memory(bias_md, eng, bias.data());
+  auto dst_memory = memory(dst_md, eng);
+
+  auto dense_desc = inner_product_forward::desc(
+      prop_kind::forward_inference, data_md, weight_md, bias_md, dst_md);
+  auto dense_prim_desc = inner_product_forward::primitive_desc(dense_desc, eng);
+  assert(dst_md == dense_prim_desc.dst_desc());
+
+  auto dense = inner_product_forward(dense_prim_desc);
+  dense.execute(s, {{DNNL_ARG_SRC, data_memory},
+                    {DNNL_ARG_WEIGHTS, weight_memory},
+                    {DNNL_ARG_BIAS, bias_memory},
+                    {DNNL_ARG_DST, dst_memory}});
+  s.wait();
+  read_from_dnnl_memory(out, dst_memory);
+}
+
+extern "C" void dnnl_relu(float* data, float* out, int p_N_, int p_C_, int p_H_,
+                          int p_W_) {
+  using tag = memory::format_tag;
+  using dt = memory::data_type;
+
+  engine eng(engine::kind::cpu, 0);
+  stream s(eng);
+
+  memory::dims data_tz = {p_N_, p_C_, p_H_, p_W_};
+
+  auto data_md = memory::desc{{data_tz}, dt::f32, tag::nchw};
+
+  auto data_memory = memory(data_md, eng, data);
+  auto dst_memory = memory(data_md, eng);
+
+  auto relu_desc = eltwise_forward::desc(prop_kind::forward_inference,
+                                         algorithm::eltwise_relu, data_md, 0);
+  auto relu_prim_desc = eltwise_forward::primitive_desc(relu_desc, eng);
+  assert(data_md == relu_prim_desc.dst_desc());
+
+  auto relu = eltwise_forward(relu_prim_desc);
+  relu.execute(s, {{DNNL_ARG_SRC, data_memory}, {DNNL_ARG_DST, dst_memory}});
+  s.wait();
+  read_from_dnnl_memory(out, dst_memory);
+}
+
+extern "C" void dnnl_bn(float* data, float* gamma, float* beta, float* mean,
+                        float* variance, float* out, int p_N_, int p_C_,
+                        int p_H_, int p_W_, int p_E_) {
+  using tag = memory::format_tag;
+  using dt = memory::data_type;
+
+  engine eng(engine::kind::cpu, 0);
+  stream s(eng);
+
+  memory::dims data_tz = {p_N_, p_C_, p_H_, p_W_};
+
+  auto data_md = memory::desc{{data_tz}, dt::f32, tag::nchw};
+
+  auto data_memory = memory(data_md, eng, data);
+  auto dst_memory = memory(data_md, eng);
+
+  auto bn_desc = batch_normalization_forward::desc(
+      prop_kind::forward_inference, data_md, p_E_,
+      normalization_flags::use_global_stats |
+          normalization_flags::use_scale_shift);
+  auto bn_prim_desc = batch_normalization_forward::primitive_desc(bn_desc, eng);
+  assert(data_md == bn_prim_desc.dst_desc());
+
+  float* weight = reinterpret_cast<float*>(malloc(sizeof(float) * 2 * p_C_));
+  memcpy(weight, gamma, sizeof(float) * p_C_);
+  memcpy(weight + p_C_, beta, sizeof(float) * p_C_);
+
+  auto weight_memory = memory(bn_prim_desc.weights_desc(), eng, weight);
+  auto mean_memory = memory(bn_prim_desc.mean_desc(), eng, mean);
+  auto variance_memory = memory(bn_prim_desc.variance_desc(), eng, variance);
+
+  auto bn = batch_normalization_forward(bn_prim_desc);
+  bn.execute(s, {{DNNL_ARG_SRC, data_memory},
+                 {DNNL_ARG_DST, dst_memory},
+                 {DNNL_ARG_SCALE_SHIFT, weight_memory},
+                 {DNNL_ARG_MEAN, mean_memory},
+                 {DNNL_ARG_VARIANCE, variance_memory}});
+  s.wait();
+  read_from_dnnl_memory(out, dst_memory);
+  free(weight);
+}
+
+extern "C" void dnnl_add(float* data, float* weight, float* out, int p_N_,
+                         int p_C_, int p_H_, int p_W_) {
+  using tag = memory::format_tag;
+  using dt = memory::data_type;
+
+  engine eng(engine::kind::cpu, 0);
+  stream s(eng);
+
+  memory::dims data_tz = {p_N_, p_C_, p_H_, p_W_};
+
+  auto data_md = memory::desc{{data_tz}, dt::f32, tag::nchw};
+  auto weight_md = memory::desc({{data_tz}, dt::f32, tag::nchw});
+  auto dst_md = memory::desc({{data_tz}, dt::f32, tag::nchw});
+
+  auto data_memory = memory(data_md, eng, data);
+  auto weight_memory = memory(weight_md, eng, weight);
+  auto dst_memory = memory(dst_md, eng);
+
+  auto add_desc =
+      binary::desc(algorithm::binary_add, data_md, weight_md, dst_md);
+  auto add_prim_desc = binary::primitive_desc(add_desc, eng);
+  assert(dst_md == add_prim_desc.dst_desc());
+
+  auto add = binary(add_prim_desc);
+  add.execute(s, {{DNNL_ARG_SRC_0, data_memory},
+                  {DNNL_ARG_SRC_1, weight_memory},
+                  {DNNL_ARG_DST, dst_memory}});
+  s.wait();
+  read_from_dnnl_memory(out, dst_memory);
+}
+
+}  // namespace contrib
+}  // namespace runtime
+}  // namespace tvm
diff --git a/src/runtime/contrib/dnnl/dnnl_kernel.h b/src/runtime/contrib/dnnl/dnnl_kernel.h
new file mode 100644
index 000000000000..4d0b100b92ec
--- /dev/null
+++ b/src/runtime/contrib/dnnl/dnnl_kernel.h
@@ -0,0 +1,56 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * \file src/runtime/contrib/dnnl/dnnl_kernel.h
+ * \brief Use external dnnl library kernels.
+ */
+
+#ifndef TVM_RUNTIME_CONTRIB_DNNL_DNNL_KERNEL_H_
+#define TVM_RUNTIME_CONTRIB_DNNL_DNNL_KERNEL_H_
+
+#include <tvm/runtime/c_runtime_api.h>
+#include "dnnl.hpp"
+
+namespace tvm {
+namespace runtime {
+namespace contrib {
+
+using namespace dnnl;
+
+extern "C" TVM_DLL void dnnl_conv2d(float* data, float* weights, float* out, int p_N_, int p_C_,
+                                    int p_H_, int p_W_, int p_O_, int p_G_, int p_Ph_, int p_Pw_,
+                                    int p_Kh_, int p_Kw_, int p_Sh_, int p_Sw_);
+
+extern "C" TVM_DLL void dnnl_dense(float* data, float* weight, float* out, int p_B_, int p_I_,
+                                   int p_O_);
+
+extern "C" TVM_DLL void dnnl_relu(float* data, float* out, int p_N_, int p_C_, int p_H_, int p_W_);
+
+extern "C" TVM_DLL void dnnl_bn(float* data, float* gamma, float* beta, float* mean,
+                                float* variance, float* out, int p_n_, int p_c_, int p_h_, int p_w_,
+                                int p_e_);
+
+extern "C" TVM_DLL void dnnl_add(float* data, float* weight, float* out, int p_n_, int p_c_,
+                                 int p_h_, int p_w_);
+
+}  // namespace contrib
+}  // namespace runtime
+}  // namespace tvm
+#endif  // TVM_RUNTIME_CONTRIB_DNNL_DNNL_KERNEL_H_
diff --git a/src/runtime/library_module.cc b/src/runtime/library_module.cc
index 423848a8fba8..d3283bc19767 100644
--- a/src/runtime/library_module.cc
+++ b/src/runtime/library_module.cc
@@ -126,6 +126,7 @@ void ImportModuleBlob(const char* mblob, std::vector<Module>* mlist) {
   for (uint64_t i = 0; i < size; ++i) {
     std::string tkey;
     CHECK(stream->Read(&tkey));
+    if (tkey == "c") continue;
     std::string fkey = "module.loadbinary_" + tkey;
     const PackedFunc* f = Registry::Get(fkey);
     CHECK(f != nullptr)
diff --git a/tests/python/relay/test_external_codegen.py b/tests/python/relay/test_external_codegen.py
new file mode 100644
index 000000000000..fb0a8a2494e9
--- /dev/null
+++ b/tests/python/relay/test_external_codegen.py
@@ -0,0 +1,228 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""Unit tests for graph partitioning."""
+import os
+import sys
+import numpy as np
+import pytest
+
+import tvm
+import tvm.relay.testing
+import tvm.relay.transform
+from tvm import relay
+from tvm.contrib import util
+
+def check_result(mod, map_inputs, out_shape, result, tol=1e-5):
+    if sys.platform == "win32":
+        print("Skip test on Windows for now")
+        return
+
+    with relay.build_config(opt_level=3, disabled_pass=["AlterOpLayout"]):
+        json, lib, _ = relay.build(mod, "llvm")
+    test_dir = os.path.dirname(os.path.realpath(os.path.expanduser(__file__)))
+    source_dir = os.path.join(test_dir, "..", "..", "..")
+    contrib_path = os.path.join(source_dir, "src", "runtime", "contrib")
+
+    kwargs = {}
+    kwargs["options"] = ["-O2", "-std=c++11", "-I" + contrib_path]
+    tmp_path = util.tempdir()
+    lib_name = 'lib.so'
+    lib_path = tmp_path.relpath(lib_name)
+    lib.export_library(lib_path, fcompile=False, **kwargs)
+    lib = tvm.module.load(lib_path)
+
+    ctx = tvm.cpu()
+    rt_mod = tvm.contrib.graph_runtime.create(json, lib, ctx)
+
+    for name, data in map_inputs.items():
+        rt_mod.set_input(name, data)
+
+    rt_mod.run()
+    out = tvm.nd.empty(out_shape, ctx=ctx)
+    out = rt_mod.get_output(0, out)
+
+    tvm.testing.assert_allclose(out.asnumpy(), result, rtol=tol, atol=tol)
+
+
+def set_external_func_attr(func, compiler, ext_symbol):
+    func = func.set_attribute("Primitive", tvm.expr.IntImm("int32", 1))
+    func = func.set_attribute("Compiler", tvm.expr.StringImm(compiler))
+    func = func.set_attribute("ExternalSymbol", tvm.expr.StringImm(ext_symbol))
+    return func
+
+
+def test_multi_node_subgraph():
+    x = relay.var('x', shape=(10, 10))
+    w0 = relay.var('w0', shape=(10, 10))
+    w1 = relay.var('w1', shape=(10, 10))
+    w2 = relay.var('w2', shape=(10, 10))
+    w3 = relay.var('w3', shape=(10, 10))
+    w4 = relay.var('w4', shape=(10, 10))
+    w5 = relay.var('w5', shape=(10, 10))
+    w6 = relay.var('w6', shape=(10, 10))
+    w7 = relay.var('w7', shape=(10, 10))
+
+    # subgraph0
+    x0 = relay.var('x0', shape=(10, 10))
+    w00 = relay.var('w00', shape=(10, 10))
+    w01 = relay.var('w01', shape=(10, 10))
+    w02 = relay.var('w02', shape=(10, 10))
+    z00 = relay.add(x0, w00)
+    p00 = relay.subtract(z00, w01)
+    q00 = relay.multiply(p00, w02)
+    subgraph0 = relay.Function([x0, w00, w01, w02], q00)
+    subgraph0 = set_external_func_attr(subgraph0, "ccompiler", "ccompiler_0")
+    call0 = relay.Call(subgraph0, [x, w0, w1, w2])
+
+    # subgraph1
+    x1 = relay.var('x1', shape=(10, 10))
+    w10 = relay.var('w10', shape=(10, 10))
+    w11 = relay.var('w11', shape=(10, 10))
+    w12 = relay.var('w12', shape=(10, 10))
+    z10 = relay.add(x1, w10)
+    p10 = relay.subtract(z10, w11)
+    q10 = relay.multiply(p10, w12)
+    subgraph1 = relay.Function([x1, w10, w11, w12], q10)
+    subgraph1 = set_external_func_attr(subgraph1, "ccompiler", "ccompiler_1")
+    call1 = relay.Call(subgraph1, [x, w3, w4, w5])
+
+
+    # Other parts on TVM
+    z2 = relay.add(x, w6)
+    q2 = relay.subtract(z2, w7)
+
+    r = relay.concatenate((call0, call1, q2), axis=0)
+    f = relay.Function([x, w0, w1, w2, w3, w4, w5, w6, w7], r)
+    mod = relay.Module()
+    mod["main"] = f
+    mod = relay.transform.InferType()(mod)
+
+    x_data = np.random.rand(10, 10).astype('float32')
+    w_data = []
+    for _ in range(8):
+        w_data.append(np.random.rand(10, 10).astype('float32'))
+
+    map_inputs = {"w{}".format(i): w_data[i] for i in range(8)}
+    map_inputs["x"] = x_data
+    check_result(
+        mod, map_inputs, (30, 10),
+        np.concatenate((((x_data + w_data[0]) - w_data[1]) * w_data[2],
+                        ((x_data + w_data[3]) - w_data[4]) * w_data[5],
+                        x_data + w_data[6] - w_data[7]),
+                       axis=0))
+
+
+def test_extern_gcc_single_op():
+    x = relay.var('x', shape=(8, 8))
+    y = relay.var('y', shape=(8, 8))
+
+    x0 = relay.var('x0', shape=(8, 8))
+    y0 = relay.var('y0', shape=(8, 8))
+    z = x0 + y0
+    f = relay.Function([x0, y0], z)
+    f = set_external_func_attr(f, "ccompiler", "ccompiler_0")
+    call = relay.Call(f, [x, y])
+    mod = relay.Module.from_expr(call)
+    x_data = np.random.rand(8, 8).astype('float32')
+    y_data = np.random.rand(8, 8).astype('float32')
+
+    check_result(mod, {"x": x_data, "y": y_data}, (8, 8), x_data + y_data)
+
+
+def test_extern_gcc():
+    x = relay.var('x', shape=(2, 2))
+    y = relay.var('y', shape=(2, 2))
+
+    # subgraph for mul
+    x0 = relay.var('x0', shape=(2, 2))
+    y0 = relay.var('y0', shape=(2, 2))
+    mul = x0 * y0
+    mul = relay.Function([x0, y0], mul)
+    mul = set_external_func_attr(mul, "ccompiler", "ccompiler_2")
+    call_mul = relay.Call(mul, [y, y])
+
+    # subgraph for add
+    x1 = relay.var('x1', shape=(2, 2))
+    y1 = relay.var('y1', shape=(2, 2))
+    add = x1 + y1
+    add = relay.Function([x1, y1], add)
+    add = set_external_func_attr(add, "ccompiler", "ccompiler_1")
+    call_add = relay.Call(add, [x, x])
+
+    # subgraph for sub
+    x2 = relay.var('x2', shape=(2, 2))
+    y2 = relay.var('y2', shape=(2, 2))
+    sub = x2 - y2
+    sub = relay.Function([x2, y2], sub)
+    sub = set_external_func_attr(sub, "ccompiler", "ccompiler_0")
+    call_sub = relay.Call(sub, [call_mul, call_add])
+    mod = relay.Module.from_expr(call_sub)
+
+    x_data = np.random.rand(2, 2).astype('float32')
+    y_data = np.random.rand(2, 2).astype('float32')
+
+    check_result(mod, {"x": x_data, "y": y_data}, (2, 2), (y_data * y_data) - (x_data + x_data))
+
+
+def test_extern_dnnl():
+    if not tvm.get_global_func("relay.ext.dnnl", True):
+        print("skip because DNNL codegen is not available")
+        return
+
+    dtype = 'float32'
+    ishape = (1, 32, 14, 14)
+    w1shape = (32, 1, 3, 3)
+    data0 = relay.var('data0', shape=(ishape), dtype=dtype)
+    weight0 = relay.var('weight0', shape=(w1shape), dtype=dtype)
+
+    data1 = relay.var('data0', shape=(ishape), dtype=dtype)
+    weight1 = relay.var('weight0', shape=(w1shape), dtype=dtype)
+    weight2 = relay.var('weight1', shape=(w1shape), dtype=dtype)
+    depthwise_conv2d_1 = relay.nn.conv2d(data1,
+                                         weight1,
+                                         kernel_size=(3, 3),
+                                         padding=(1, 1),
+                                         groups=32)
+    depthwise_conv2d_2 = relay.nn.conv2d(depthwise_conv2d_1,
+                                         weight2,
+                                         kernel_size=(3, 3),
+                                         padding=(1, 1),
+                                         groups=32)
+    out = relay.add(depthwise_conv2d_1, depthwise_conv2d_2)
+
+    f = relay.Function([data1, weight1, weight2], out)
+    ref_mod = relay.Module()
+    ref_mod['main'] = f
+
+    f = set_external_func_attr(f, "dnnl", "dnnl_0")
+    call = relay.Call(f, [data0, weight0, weight0])
+    mod = relay.Module.from_expr(call)
+
+    i_data = np.random.uniform(0, 1, ishape).astype(dtype)
+    w_data = np.random.uniform(0, 1, w1shape).astype(dtype)
+
+    ref_ex = relay.create_executor("graph", mod=ref_mod, ctx=tvm.cpu())
+    ref_res = ref_ex.evaluate()(i_data, w_data, w_data)
+    check_result(mod, {"data0": i_data, "weight0": w_data},
+                 (1, 32, 14, 14), ref_res.asnumpy(), tol=1e-5)
+
+
+if __name__ == "__main__":
+    test_multi_node_subgraph()
+    test_extern_gcc_single_op()
+    test_extern_gcc()
+    test_extern_dnnl()