diff --git a/test/cpp/jit/CMakeLists.txt b/test/cpp/jit/CMakeLists.txt
index 4ccb6d71591ef..50ec6bf904a21 100644
--- a/test/cpp/jit/CMakeLists.txt
+++ b/test/cpp/jit/CMakeLists.txt
@@ -11,7 +11,10 @@ target_link_libraries(torchbind_test torch)
 add_library(jitbackend_test SHARED ${JIT_TEST_ROOT}/test_backend_lib.cpp)
 target_link_libraries(jitbackend_test torch)
 
-add_library(backend_with_compiler SHARED ${JIT_TEST_ROOT}/test_backend_compiler_lib.cpp)
+add_library(backend_with_compiler SHARED
+        ${JIT_TEST_ROOT}/test_backend_compiler_lib.cpp
+        ${JIT_TEST_ROOT}/test_backend_compiler_preprocess.cpp
+        )
 target_link_libraries(backend_with_compiler torch)
 
 if(INSTALL_TEST)
diff --git a/test/cpp/jit/test_backend_compiler_lib.cpp b/test/cpp/jit/test_backend_compiler_lib.cpp
index caf4e3f0494d6..a6007790cdc55 100644
--- a/test/cpp/jit/test_backend_compiler_lib.cpp
+++ b/test/cpp/jit/test_backend_compiler_lib.cpp
@@ -106,56 +106,8 @@ class BackendWithCompiler : public PyTorchBackendInterface {
 };
 
 namespace {
-// For this backend, the actual compilation happens in preprocess function AOT.
-// Put here for demonstration of backend
-// as a whole piece. It's used when compilation is required. A dummy function
-// can be passed when there's no usage of compilation in runtime backend lib.
-c10::IValue preprocess(
-    const Module& mod,
-    const c10::Dict<IValue, IValue>& method_compile_spec) {
-  // The output of this process would produce a dictionary
-  // Key: method name.
-  // Val: compiled blob (represented by a string).
-  c10::Dict<IValue, IValue> compiled(StringType::get(), StringType::get());
-  for (const auto& method : mod.get_methods()) {
-    const auto graph = method.function().graph()->copy();
-    auto key = method.name();
-    std::stringstream ss;
-    for (const auto& node : graph->nodes()) {
-      switch (node->kind()) {
-        case prim::Constant:
-          ss << node->kind().toDisplayString() << "#"
-             << toIValue(node->output()).value();
-          break;
-        case aten::add:
-          ss << node->kind().toQualString();
-          break;
-        case aten::sub:
-          ss << node->kind().toQualString();
-          break;
-        default:
-          TORCH_CHECK(
-              false,
-              "The node of ",
-              node->kind().toQualString(),
-              " is not supported in this compiler. Source code: ",
-              node->sourceRange().str());
-          break;
-      }
-      ss << ",";
-    }
-    std::string blob = ss.str();
-    if (!blob.empty()) {
-      blob.pop_back();
-    }
-    compiled.insert(method.name(), blob);
-  }
-  return compiled;
-}
-
-static auto cls = torch::jit::backend<BackendWithCompiler>(
-    "backend_with_compiler_demo",
-    preprocess);
+constexpr auto backend_name = "backend_with_compiler_demo";
+static auto cls = torch::jit::backend<BackendWithCompiler>(backend_name);
 } // namespace
 
 } // namespace jit
diff --git a/test/cpp/jit/test_backend_compiler_preprocess.cpp b/test/cpp/jit/test_backend_compiler_preprocess.cpp
new file mode 100644
index 0000000000000..9f545d9ce3357
--- /dev/null
+++ b/test/cpp/jit/test_backend_compiler_preprocess.cpp
@@ -0,0 +1,59 @@
+#include <torch/csrc/jit/backends/backend.h>
+#include <torch/csrc/jit/backends/backend_preprocess.h>
+
+namespace torch {
+namespace jit {
+namespace {
+// For this backend, the actual compilation happens in preprocess function AOT.
+// Put here for demonstration of backend
+// as a whole piece. It's used when compilation is required. A dummy function
+// can be passed when there's no usage of compilation in runtime backend lib.
+c10::IValue preprocess(
+    const Module& mod,
+    const c10::Dict<IValue, IValue>& method_compile_spec) {
+  // The output of this process would produce a dictionary
+  // Key: method name.
+  // Val: compiled blob (represented by a string).
+  c10::Dict<IValue, IValue> compiled(StringType::get(), StringType::get());
+  for (const auto& method : mod.get_methods()) {
+    const auto graph = method.function().graph()->copy();
+    auto key = method.name();
+    std::stringstream ss;
+    for (const auto& node : graph->nodes()) {
+      switch (node->kind()) {
+        case prim::Constant:
+          ss << node->kind().toDisplayString() << "#"
+             << toIValue(node->output()).value();
+          break;
+        case aten::add:
+          ss << node->kind().toQualString();
+          break;
+        case aten::sub:
+          ss << node->kind().toQualString();
+          break;
+        default:
+          TORCH_CHECK(
+              false,
+              "The node of ",
+              node->kind().toQualString(),
+              " is not supported in this compiler. Source code: ",
+              node->sourceRange().str());
+          break;
+      }
+      ss << ",";
+    }
+    std::string blob = ss.str();
+    if (!blob.empty()) {
+      blob.pop_back();
+    }
+    compiled.insert(method.name(), blob);
+  }
+  return compiled;
+}
+
+constexpr auto backend_name = "backend_with_compiler_demo";
+static auto pre_reg = backend_preprocess_register(backend_name, preprocess);
+} // namespace
+
+} // namespace jit
+} // namespace torch
diff --git a/test/cpp/jit/test_backend_lib.cpp b/test/cpp/jit/test_backend_lib.cpp
index 5c10308f40cdf..bb234ead4b9d1 100644
--- a/test/cpp/jit/test_backend_lib.cpp
+++ b/test/cpp/jit/test_backend_lib.cpp
@@ -1,4 +1,5 @@
 #include <torch/csrc/jit/backends/backend.h>
+#include <torch/csrc/jit/backends/backend_preprocess.h>
 
 namespace torch {
 namespace jit {
@@ -73,12 +74,17 @@ c10::IValue preprocess(
   return mod._ivalue();
 }
 
+constexpr auto backend_name = "test_backend";
 static auto cls_available =
-    torch::jit::backend<TestBackend<true>>("test_backend", preprocess);
-static auto cls_unavailable = torch::jit::backend<TestBackend<false>>(
-    "test_backend_unavailable",
-    preprocess);
-} // namespace
+    torch::jit::backend<TestBackend<true>>(backend_name);
+static auto pre_reg = backend_preprocess_register(backend_name, preprocess);
+
+constexpr auto backend_unavailable_name = "test_backend_unavailable";
+static auto cls_unavailable =
+    torch::jit::backend<TestBackend<false>>(backend_unavailable_name);
+static auto pre_reg_unavailable =
+    backend_preprocess_register(backend_unavailable_name, preprocess);
 
+} // namespace
 } // namespace jit
 } // namespace torch
diff --git a/test/cpp/lite_interpreter_runtime/CMakeLists.txt b/test/cpp/lite_interpreter_runtime/CMakeLists.txt
index cf43c9083f35d..c68ea8869b4b1 100644
--- a/test/cpp/lite_interpreter_runtime/CMakeLists.txt
+++ b/test/cpp/lite_interpreter_runtime/CMakeLists.txt
@@ -6,13 +6,21 @@ set(LITE_INTERPRETER_RUNTIME_TEST_DIR
   ${TORCH_ROOT}/test/cpp/lite_interpreter_runtime/test_lite_interpreter_runtime.cpp
 )
 
+add_library(backend_with_compiler_runtime SHARED
+        ${TORCH_ROOT}/test/cpp/jit/test_backend_compiler_lib.cpp
+        ${TORCH_ROOT}/torch/csrc/jit/backends/backend_interface.cpp
+        )
+target_link_libraries(backend_with_compiler_runtime PRIVATE torch)
+
 add_executable(
   test_lite_interpreter_runtime
   ${LITE_INTERPRETER_RUNTIME_TEST_DIR})
 target_include_directories(
   test_lite_interpreter_runtime PRIVATE
-  ${ATen_CPU_INCLUDE})
-target_link_libraries(test_lite_interpreter_runtime PRIVATE torch gtest)
+  ${ATen_CPU_INCLUDE}
+)
+
+target_link_libraries(test_lite_interpreter_runtime PRIVATE torch gtest backend_with_compiler_runtime)
 
 if(INSTALL_TEST)
   install(TARGETS test_lite_interpreter_runtime DESTINATION bin)
diff --git a/test/cpp/lite_interpreter_runtime/delegate_test.ptl b/test/cpp/lite_interpreter_runtime/delegate_test.ptl
new file mode 100644
index 0000000000000..1e65c14e2ab7a
Binary files /dev/null and b/test/cpp/lite_interpreter_runtime/delegate_test.ptl differ
diff --git a/test/cpp/lite_interpreter_runtime/test_lite_interpreter_runtime.cpp b/test/cpp/lite_interpreter_runtime/test_lite_interpreter_runtime.cpp
index 852a28f7a4361..ae58b99676a6f 100644
--- a/test/cpp/lite_interpreter_runtime/test_lite_interpreter_runtime.cpp
+++ b/test/cpp/lite_interpreter_runtime/test_lite_interpreter_runtime.cpp
@@ -49,6 +49,28 @@ TEST(RunTimeTest, LoadAndForward) {
   ASSERT_EQ(result, expected_result);
 }
 
+TEST(RunTimeTest, Delegate) {
+  std::string filePath(__FILE__);
+  auto testModelFile = filePath.substr(0, filePath.find_last_of("/\\") + 1);
+  // "delegate_test.ptl" is generated from test/cpp/jit/test_backend.cpp,
+  // BackendTest.TestCompiler. This test is on target runtime. It has
+  // model running capability, but no compilation and serialization.
+  // The mobile model delegated to the "backend_with_compiler_demo" backend
+  // The model is from the jit code:
+  //  Module m("m");
+  //  m.define(R"(
+  //    def forward(self, x, h):
+  //        return x + h
+  //  )");
+  testModelFile.append("delegate_test.ptl");
+  auto mlm = _load_for_mobile(testModelFile);
+  std::vector<IValue> inputs;
+  inputs.emplace_back(2.0 * at::ones({}));
+  inputs.emplace_back(1.0 * at::ones({}));
+
+  auto mres = mlm.forward(inputs);
+  AT_ASSERT(mres.toTensor().equal(3 * at::ones({})));
+}
 } // namespace mobile
 } // namespace jit
 } // namespace torch
diff --git a/test/custom_backend/custom_backend.cpp b/test/custom_backend/custom_backend.cpp
index dd67f4db2170d..ddcdc7bca0268 100644
--- a/test/custom_backend/custom_backend.cpp
+++ b/test/custom_backend/custom_backend.cpp
@@ -1,10 +1,12 @@
 #include "custom_backend.h"
+#include <torch/csrc/jit/backends/backend_preprocess.h>
 
 namespace torch {
 namespace custom_backend {
 namespace {
 constexpr auto kBackendName = "custom_backend";
-static auto cls = torch::jit::backend<CustomBackend>(kBackendName, preprocess);
+static auto cls = torch::jit::backend<CustomBackend>(kBackendName);
+static auto pre_reg = torch::jit::backend_preprocess_register(kBackendName, preprocess);
 }
 
 std::string getBackendName() {
diff --git a/test/custom_backend/custom_backend.h b/test/custom_backend/custom_backend.h
index b1f8ca13609dc..4829d2169d521 100644
--- a/test/custom_backend/custom_backend.h
+++ b/test/custom_backend/custom_backend.h
@@ -1,4 +1,5 @@
 #include <torch/csrc/jit/backends/backend.h>
+#include <torch/csrc/jit/api/module.h>
 
 namespace torch {
 namespace custom_backend {
diff --git a/torch/csrc/jit/backends/backend.h b/torch/csrc/jit/backends/backend.h
index 2d648d81bf298..995cf373a9f6e 100644
--- a/torch/csrc/jit/backends/backend.h
+++ b/torch/csrc/jit/backends/backend.h
@@ -2,12 +2,86 @@
 
 #include <ATen/core/builtin_function.h>
 #include <ATen/core/stack.h>
-#include <torch/csrc/jit/backends/backend_detail.h>
 #include <torch/csrc/jit/backends/backend_interface.h>
 #include <torch/custom_class.h>
 
 namespace torch {
 namespace jit {
+namespace {
+c10::FunctionSchema getIsAvailableSchema() {
+  c10::Argument self("self", c10::AnyType::get());
+  c10::Argument available("available", c10::BoolType::get());
+  c10::FunctionSchema preprocessor_schema(
+      "is_available",
+      /*overload_name=*/"",
+      /*arguments=*/{self},
+      /*returns=*/{available});
+  return preprocessor_schema;
+}
+
+constexpr static auto kBackendsNamespace = "__backends__";
+
+c10::FunctionSchema getCompileSchema() {
+  c10::Argument self("self", c10::AnyType::get());
+  c10::Argument mod("processed", c10::AnyType::get());
+  auto any_dict_ty =
+      c10::DictType::create(c10::StringType::get(), c10::AnyType::get());
+  c10::Argument method_compile_spec("method_compile_spec", any_dict_ty);
+  c10::Argument handles("handles", any_dict_ty);
+
+  c10::FunctionSchema compile_schema(
+      "compile",
+      /*overload_name=*/"",
+      /*arguments=*/{self, mod, method_compile_spec},
+      /*returns=*/{handles});
+  return compile_schema;
+}
+
+c10::FunctionSchema getExecuteSchema() {
+  auto any_list_ty = c10::ListType::create(c10::AnyType::get());
+  c10::Argument self("self", c10::AnyType::get());
+  c10::Argument handle("handle", c10::AnyType::get());
+  c10::Argument input("input", any_list_ty);
+  c10::Argument output("output", any_list_ty);
+  return c10::FunctionSchema(
+      "execute",
+      /*overload_name=*/"",
+      /*arguments=*/{self, handle, input},
+      /*returns=*/{output});
+}
+
+template <typename TBackendInterface>
+std::function<void(Stack&)> getIsAvailableFunc() {
+  return [](Stack& stack) {
+    auto self = pop(stack).toCustomClass<TBackendInterface>();
+    auto ret = self->is_available();
+    push(stack, ret);
+  };
+}
+
+template <typename TBackendInterface>
+std::function<void(Stack&)> getCompileFunc() {
+  return [](Stack& stack) {
+    auto method_compile_spec = pop(stack).toGenericDict();
+    auto processed = pop(stack);
+    auto self = pop(stack).toCustomClass<TBackendInterface>();
+    auto ret = self->compile(processed, method_compile_spec);
+    push(stack, ret);
+  };
+}
+
+template <typename TBackendInterface>
+std::function<void(Stack&)> getExecuteFunc() {
+  return [](Stack& stack) {
+    auto args = pop(stack);
+    auto handle = pop(stack);
+    auto self = pop(stack);
+    auto backend = self.toCustomClass<TBackendInterface>();
+    auto res = backend->execute(handle, args.toList());
+    push(stack, res);
+  };
+}
+} // namespace
 
 // Static registration API for backends.
 template <class TBackendInterface>
@@ -20,26 +94,22 @@ class backend {
  public:
   // Registers a new backend with /p name, and the given /p preprocess
   // function.
-  backend(
-      const std::string& name,
-      const detail::BackendPreprocessFunction& preprocess)
-      : backend_name_(name) {
-    detail::registerBackendPreprocessFunction(name, preprocess);
+  backend(const std::string& name) : backend_name_(name) {
     static auto cls =
-        torch::class_<TBackendInterface>(detail::kBackendsNamespace, name)
+        torch::class_<TBackendInterface>(kBackendsNamespace, name)
             .def(torch::init<>())
             ._def_unboxed(
                 "is_available",
-                detail::getIsAvailableFunc<TBackendInterface>(),
-                detail::getIsAvailableSchema())
+                getIsAvailableFunc<TBackendInterface>(),
+                getIsAvailableSchema())
             ._def_unboxed(
                 "compile",
-                detail::getCompileFunc<TBackendInterface>(),
-                detail::getCompileSchema())
+                getCompileFunc<TBackendInterface>(),
+                getCompileSchema())
             ._def_unboxed(
                 "execute",
-                detail::getExecuteFunc<TBackendInterface>(),
-                detail::getExecuteSchema());
+                getExecuteFunc<TBackendInterface>(),
+                getExecuteSchema());
   }
 };
 
diff --git a/torch/csrc/jit/backends/backend_detail.cpp b/torch/csrc/jit/backends/backend_detail.cpp
index 5dbd3dcdec053..9d0e44f451794 100644
--- a/torch/csrc/jit/backends/backend_detail.cpp
+++ b/torch/csrc/jit/backends/backend_detail.cpp
@@ -1,7 +1,7 @@
 #include <torch/csrc/jit/backends/backend_detail.h>
 
-#include <ATen/core/builtin_function.h>
 #include <ATen/core/jit_type.h>
+#include <torch/csrc/jit/backends/backend.h>
 #include <torch/csrc/jit/backends/backend_resolver.h>
 #include <torch/csrc/jit/frontend/code_template.h>
 
@@ -10,46 +10,6 @@
 namespace torch {
 namespace jit {
 namespace detail {
-c10::FunctionSchema getIsAvailableSchema() {
-  c10::Argument self("self", c10::AnyType::get());
-  c10::Argument available("available", c10::BoolType::get());
-  c10::FunctionSchema preprocessor_schema(
-      "is_available",
-      /*overload_name=*/"",
-      /*arguments=*/{self},
-      /*returns=*/{available});
-  return preprocessor_schema;
-}
-
-c10::FunctionSchema getCompileSchema() {
-  c10::Argument self("self", c10::AnyType::get());
-  c10::Argument mod("processed", c10::AnyType::get());
-  auto any_dict_ty =
-      c10::DictType::create(c10::StringType::get(), c10::AnyType::get());
-  c10::Argument method_compile_spec("method_compile_spec", any_dict_ty);
-  c10::Argument handles("handles", any_dict_ty);
-
-  c10::FunctionSchema compile_schema(
-      "compile",
-      /*overload_name=*/"",
-      /*arguments=*/{self, mod, method_compile_spec},
-      /*returns=*/{handles});
-  return compile_schema;
-}
-
-c10::FunctionSchema getExecuteSchema() {
-  auto any_list_ty = c10::ListType::create(c10::AnyType::get());
-  c10::Argument self("self", c10::AnyType::get());
-  c10::Argument handle("handle", c10::AnyType::get());
-  c10::Argument input("input", any_list_ty);
-  c10::Argument output("output", any_list_ty);
-  return c10::FunctionSchema(
-      "execute",
-      /*overload_name=*/"",
-      /*arguments=*/{self, handle, input},
-      /*returns=*/{output});
-}
-
 namespace {
 std::unordered_map<std::string, BackendPreprocessFunction>&
 backendPreprocessFunctions() {
@@ -93,7 +53,7 @@ Module codegen_backend_module(
       {"__torch__",
        "torch",
        "classes",
-       detail::kBackendsNamespace,
+       kBackendsNamespace,
        backend_name});
   // TODO: Validate method_compile_spec.
 
diff --git a/torch/csrc/jit/backends/backend_detail.h b/torch/csrc/jit/backends/backend_detail.h
index 1d75378017566..ffc9ce07b34ef 100644
--- a/torch/csrc/jit/backends/backend_detail.h
+++ b/torch/csrc/jit/backends/backend_detail.h
@@ -3,7 +3,6 @@
 #include <torch/csrc/jit/api/module.h>
 
 #include <ATen/core/jit_type.h>
-#include <ATen/core/stack.h>
 
 #include <functional>
 
@@ -11,44 +10,6 @@ namespace torch {
 namespace jit {
 namespace detail {
 
-constexpr static auto kBackendsNamespace = "__backends__";
-
-c10::FunctionSchema TORCH_API getIsAvailableSchema();
-c10::FunctionSchema TORCH_API getCompileSchema();
-c10::FunctionSchema TORCH_API getExecuteSchema();
-
-template <typename TBackendInterface>
-std::function<void(Stack&)> getIsAvailableFunc() {
-  return [](Stack& stack) {
-    auto self = pop(stack).toCustomClass<TBackendInterface>();
-    auto ret = self->is_available();
-    push(stack, ret);
-  };
-}
-
-template <typename TBackendInterface>
-std::function<void(Stack&)> getCompileFunc() {
-  return [](Stack& stack) {
-    auto method_compile_spec = pop(stack).toGenericDict();
-    auto processed = pop(stack);
-    auto self = pop(stack).toCustomClass<TBackendInterface>();
-    auto ret = self->compile(processed, method_compile_spec);
-    push(stack, ret);
-  };
-}
-
-template <typename TBackendInterface>
-std::function<void(Stack&)> getExecuteFunc() {
-  return [](Stack& stack) {
-    auto args = pop(stack);
-    auto handle = pop(stack);
-    auto self = pop(stack);
-    auto backend = self.toCustomClass<TBackendInterface>();
-    auto res = backend->execute(handle, args.toList());
-    push(stack, res);
-  };
-}
-
 using BackendPreprocessFunction =
     std::function<c10::IValue(const Module&, const c10::Dict<IValue, IValue>&)>;
 
diff --git a/torch/csrc/jit/backends/backend_preprocess.h b/torch/csrc/jit/backends/backend_preprocess.h
new file mode 100644
index 0000000000000..0a256134aa96e
--- /dev/null
+++ b/torch/csrc/jit/backends/backend_preprocess.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include <torch/csrc/jit/backends/backend_detail.h>
+namespace torch {
+namespace jit {
+class backend_preprocess_register {
+  std::string backend_name_;
+
+ public:
+  backend_preprocess_register(
+      const std::string& name,
+      const detail::BackendPreprocessFunction& preprocess)
+      : backend_name_(name) {
+    detail::registerBackendPreprocessFunction(name, preprocess);
+  }
+};
+} // namespace jit
+} // namespace torch