diff --git a/caffe2/CMakeLists.txt b/caffe2/CMakeLists.txt
index c2039be377b..855484cedff 100644
--- a/caffe2/CMakeLists.txt
+++ b/caffe2/CMakeLists.txt
@@ -106,12 +106,10 @@ endif()
 add_subdirectory(core)
 add_subdirectory(serialize)
 add_subdirectory(utils)
-if(BUILD_CAFFE2)
-  add_subdirectory(perfkernels)
-endif()
+add_subdirectory(perfkernels)
 
 # Skip modules that are not used by libtorch mobile yet.
-if(BUILD_CAFFE2 AND (NOT INTERN_BUILD_MOBILE OR BUILD_CAFFE2_MOBILE))
+if(NOT INTERN_BUILD_MOBILE OR BUILD_CAFFE2_MOBILE)
   add_subdirectory(contrib)
   add_subdirectory(predictor)
   add_subdirectory(predictor/emulator)
@@ -149,9 +147,6 @@ if(BUILD_CAFFE2 AND (NOT INTERN_BUILD_MOBILE OR BUILD_CAFFE2_MOBILE))
   # add_subdirectory(test) # todo: use caffe2_gtest_main instead of gtest_main because we will need to call GlobalInit
   add_subdirectory(transforms)
 endif()
-if(NOT BUILD_CAFFE2)
-  add_subdirectory(proto)
-endif()
 
 # Advanced: if we have allow list specified, we will do intersections for all
 # main lib srcs.
@@ -468,21 +463,11 @@ if(NOT INTERN_BUILD_MOBILE OR NOT BUILD_CAFFE2_MOBILE)
       ${TORCH_SRC_DIR}/csrc/jit/serialization/onnx.cpp
       ${TORCH_SRC_DIR}/csrc/jit/serialization/export.cpp
       ${TORCH_SRC_DIR}/csrc/jit/serialization/export_module.cpp
+      ${TORCH_SRC_DIR}/csrc/jit/serialization/import_legacy.cpp
       ${TORCH_SRC_DIR}/csrc/jit/codegen/fuser/cpu/fused_kernel.cpp
       ${TORCH_SRC_DIR}/csrc/jit/api/module_save.cpp
       ${TORCH_SRC_DIR}/csrc/utils/byte_order.cpp
     )
-    # Disable legacy import of building without Caffe2 support
-    if(BUILD_CAFFE2)
-      list(APPEND TORCH_SRCS
-        ${TORCH_SRC_DIR}/csrc/jit/serialization/import_legacy.cpp
-      )
-    else()
-      set_source_files_properties(
-        ${TORCH_SRC_DIR}/csrc/jit/serialization/import.cpp
-        PROPERTIES COMPILE_FLAGS "-DC10_DISABLE_LEGACY_IMPORT"
-      )
-    endif()
     if(USE_DISTRIBUTED)
       append_filelist("libtorch_distributed_sources" TORCH_SRCS)
     endif()
@@ -1396,7 +1381,6 @@ if(BUILD_PYTHON)
   endif()
 
   # ---[ Python.
-  if(BUILD_CAFFE2)
   add_library(caffe2_pybind11_state MODULE ${Caffe2_CPU_PYTHON_SRCS})
   if(NOT MSVC)
     set_target_properties(caffe2_pybind11_state PROPERTIES COMPILE_FLAGS "-fvisibility=hidden")
@@ -1508,7 +1492,6 @@ if(BUILD_PYTHON)
   # Create a custom target that copies all python files.
   file(GLOB_RECURSE PYTHON_SRCS RELATIVE ${PROJECT_SOURCE_DIR}
        "${PROJECT_SOURCE_DIR}/caffe2/*.py")
-  endif()
 
   # generated pb files are copied from build/caffe2 to caffe2
   # if we copied them back to build this would create a build cycle
diff --git a/caffe2/core/CMakeLists.txt b/caffe2/core/CMakeLists.txt
index 91cd11551b3..4003093f635 100644
--- a/caffe2/core/CMakeLists.txt
+++ b/caffe2/core/CMakeLists.txt
@@ -1,4 +1,4 @@
-if((NOT BUILD_CAFFE2) OR (INTERN_BUILD_MOBILE AND NOT BUILD_CAFFE2_MOBILE))
+if(INTERN_BUILD_MOBILE AND NOT BUILD_CAFFE2_MOBILE)
   list(APPEND Caffe2_CPU_SRCS
     "${CMAKE_CURRENT_SOURCE_DIR}/common.cc"
   )
diff --git a/caffe2/proto/CMakeLists.txt b/caffe2/proto/CMakeLists.txt
index 9dc4b4a86cb..ac48fd7e50a 100644
--- a/caffe2/proto/CMakeLists.txt
+++ b/caffe2/proto/CMakeLists.txt
@@ -1,8 +1,4 @@
-if(BUILD_CAFFE2)
-  file(GLOB Caffe2_PROTOBUF_FILES "${CMAKE_CURRENT_SOURCE_DIR}/*.proto")
-else()
-  set(Caffe2_PROTOBUF_FILES "${CMAKE_CURRENT_SOURCE_DIR}/torch.proto;${CMAKE_CURRENT_SOURCE_DIR}/caffe2.proto")
-endif()
+file(GLOB Caffe2_PROTOBUF_FILES "${CMAKE_CURRENT_SOURCE_DIR}/*.proto")
 
 caffe2_protobuf_generate_cpp_py(Caffe2_PROTO_SRCS Caffe2_PROTO_HEADERS Caffe2_PROTO_PY ${Caffe2_PROTOBUF_FILES})
 
diff --git a/caffe2/utils/CMakeLists.txt b/caffe2/utils/CMakeLists.txt
index 798985953b8..19b0b430e72 100644
--- a/caffe2/utils/CMakeLists.txt
+++ b/caffe2/utils/CMakeLists.txt
@@ -1,14 +1,9 @@
-if((NOT BUILD_CAFFE2) OR (INTERN_BUILD_MOBILE AND NOT BUILD_CAFFE2_MOBILE))
+if(INTERN_BUILD_MOBILE AND NOT BUILD_CAFFE2_MOBILE)
   list(APPEND Caffe2_CPU_SRCS
     utils/string_utils.cc
     utils/threadpool/pthreadpool-cpp.cc
     utils/threadpool/ThreadPool.cc
   )
-  if(NOT BUILD_CAFFE2)
-    list(APPEND Caffe2_CPU_SRCS
-      utils/proto_wrap.cc
-    )
-  endif()
   set(Caffe2_CPU_SRCS ${Caffe2_CPU_SRCS} PARENT_SCOPE)
   return()
 endif()
diff --git a/torch/csrc/jit/serialization/import.cpp b/torch/csrc/jit/serialization/import.cpp
index a5810f23505..8831b22255a 100644
--- a/torch/csrc/jit/serialization/import.cpp
+++ b/torch/csrc/jit/serialization/import.cpp
@@ -3,7 +3,7 @@
 #include <ATen/core/ivalue_inl.h>
 #include <c10/util/Exception.h>
 #include <torch/csrc/jit/serialization/import_export_helpers.h>
-#if !defined(C10_MOBILE) && !defined(C10_DISABLE_LEGACY_IMPORT)
+#ifndef C10_MOBILE
 #include <torch/csrc/jit/serialization/import_legacy.h>
 #endif
 #include <torch/csrc/jit/frontend/script_type_parser.h>
@@ -256,7 +256,7 @@ Module ScriptModuleDeserializer::deserialize(
     }
   }
   if (reader_->hasRecord("model.json")) {
-#if !defined(C10_MOBILE) && !defined(C10_DISABLE_LEGACY_IMPORT)
+#ifndef C10_MOBILE
     return torch::jit::LEGACY_deserialize(
         compilation_unit_, std::move(reader_), device_);
 #else