diff --git a/cmake/Codegen.cmake b/cmake/Codegen.cmake
index dda9a52b5d2973..5bd8b90b6bc9ed 100644
--- a/cmake/Codegen.cmake
+++ b/cmake/Codegen.cmake
@@ -201,11 +201,31 @@ if(INTERN_BUILD_ATEN_OPS)
       ${GEN_VULKAN_FLAGS}
   )
 
+  file(GLOB_RECURSE headers_templates "${CMAKE_CURRENT_LIST_DIR}/../aten/src/ATen/templates/*\.h")
+  file(GLOB_RECURSE sources_templates "${CMAKE_CURRENT_LIST_DIR}/../aten/src/ATen/templates/*\.cpp")
+  set(declarations_yaml_templates "")
+
+  file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/aten/src/ATen)
+  file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/aten/src/ATen/core)
+
   foreach(gen_type "headers" "sources" "declarations_yaml")
+    # The codegen outputs may change dynamically as PyTorch is
+    # developed, but add_custom_command only supports dynamic inputs.
+    #
+    # We work around this by generating a .cmake file which is
+    # included below to set the list of output files. If that file
+    # ever changes then cmake will be re-run automatically because it
+    # was included and so we get fully dynamic outputs.
+
+    set("GEN_COMMAND_${gen_type}"
+        ${GEN_COMMAND}
+        --generate ${gen_type}
+        --output-dependencies ${CMAKE_BINARY_DIR}/aten/src/ATen/generated_${gen_type}.cmake
+    )
+
+    # Dry run to bootstrap the output variables
     execute_process(
-        COMMAND ${GEN_COMMAND}
-          --generate ${gen_type}
-          --output-dependencies ${CMAKE_BINARY_DIR}/aten/src/ATen/generated_${gen_type}.txt
+        COMMAND ${GEN_COMMAND_${gen_type}} --dry-run
         RESULT_VARIABLE RETURN_VALUE
         WORKING_DIRECTORY ${CMAKE_CURRENT_LIST_DIR}/..
     )
@@ -214,43 +234,22 @@ if(INTERN_BUILD_ATEN_OPS)
       message(FATAL_ERROR "Failed to get generated_${gen_type} list")
     endif()
 
-    file(READ "${CMAKE_BINARY_DIR}/aten/src/ATen/generated_${gen_type}.txt" "generated_${gen_type}")
-    file(READ "${CMAKE_BINARY_DIR}/aten/src/ATen/generated_${gen_type}.txt-cuda" "cuda_generated_${gen_type}")
-    file(READ "${CMAKE_BINARY_DIR}/aten/src/ATen/generated_${gen_type}.txt-core" "core_generated_${gen_type}")
-  endforeach()
-
-  file(GLOB_RECURSE header_templates "${CMAKE_CURRENT_LIST_DIR}/../aten/src/ATen/templates/*\.h")
-  file(GLOB_RECURSE source_templates "${CMAKE_CURRENT_LIST_DIR}/../aten/src/ATen/templates/*\.cpp")
-
-  file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/aten/src/ATen)
-  file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/aten/src/ATen/core)
-
-  add_custom_command(
-    OUTPUT ${generated_headers} ${cuda_generated_headers} ${core_generated_headers}
-    COMMAND ${GEN_COMMAND} --generate headers
-    DEPENDS ${all_python} ${header_templates}
-      ${CMAKE_CURRENT_LIST_DIR}/../aten/src/ATen/native/native_functions.yaml
-    WORKING_DIRECTORY ${CMAKE_CURRENT_LIST_DIR}/..
-    )
-
-  add_custom_command(
-    OUTPUT ${generated_sources} ${cuda_generated_sources} ${core_generated_sources}
-    COMMAND ${GEN_COMMAND} --generate sources
-    DEPENDS ${all_python} ${source_templates}
-      ${CMAKE_CURRENT_LIST_DIR}/../aten/src/ATen/native/native_functions.yaml
-    WORKING_DIRECTORY ${CMAKE_CURRENT_LIST_DIR}/..
-    )
-
-  add_custom_command(
-    OUTPUT
-      ${generated_declarations_yaml}
-      ${cuda_generated_declarations_yaml}
-      ${core_generated_declarations_yaml}
-    COMMAND ${GEN_COMMAND} --generate declarations_yaml
-    DEPENDS ${all_python}
-      ${CMAKE_CURRENT_LIST_DIR}/../aten/src/ATen/native/native_functions.yaml
-    WORKING_DIRECTORY ${CMAKE_CURRENT_LIST_DIR}/..
+    include("${CMAKE_BINARY_DIR}/aten/src/ATen/generated_${gen_type}.cmake")
+    include("${CMAKE_BINARY_DIR}/aten/src/ATen/core_generated_${gen_type}.cmake")
+    include("${CMAKE_BINARY_DIR}/aten/src/ATen/cuda_generated_${gen_type}.cmake")
+
+    add_custom_command(
+      COMMENT "Generating ATen ${gen_type}"
+      OUTPUT ${generated_${gen_type}} ${cuda_generated_${gen_type}} ${core_generated_${gen_type}}
+        ${CMAKE_BINARY_DIR}/aten/src/ATen/generated_${gen_type}.cmake
+        ${CMAKE_BINARY_DIR}/aten/src/ATen/core_generated_${gen_type}.cmake
+        ${CMAKE_BINARY_DIR}/aten/src/ATen/cuda_generated_${gen_type}.cmake
+      COMMAND ${GEN_COMMAND_${gen_type}}
+      DEPENDS ${all_python} ${${gen_type}_templates}
+        ${CMAKE_CURRENT_LIST_DIR}/../aten/src/ATen/native/native_functions.yaml
+      WORKING_DIRECTORY ${CMAKE_CURRENT_LIST_DIR}/..
     )
+  endforeach()
 
   # Generated headers used from a CUDA (.cu) file are
   # not tracked correctly in CMake. We make the libATen.so depend explicitly
diff --git a/tools/codegen/gen.py b/tools/codegen/gen.py
index d43d0c9a561ba5..072b83c3d0dbac 100644
--- a/tools/codegen/gen.py
+++ b/tools/codegen/gen.py
@@ -1200,6 +1200,9 @@ def main() -> None:
         '-o',
         '--output-dependencies',
         help='output a list of dependencies into the given file and exit')
+    parser.add_argument(
+        '--dry-run', action='store_true',
+        help='run without writing any files (still updates outputs)')
     parser.add_argument(
         '-d', '--install_dir', help='output directory',
         default='build/aten/src/ATen')
@@ -1271,7 +1274,7 @@ def main() -> None:
     pathlib.Path(core_install_dir).mkdir(parents=True, exist_ok=True)
 
     def make_file_manager(install_dir: str) -> FileManager:
-        return FileManager(install_dir=install_dir, template_dir=template_dir, dry_run=options.output_dependencies)
+        return FileManager(install_dir=install_dir, template_dir=template_dir, dry_run=options.dry_run)
 
     core_fm = make_file_manager(core_install_dir)
     cpu_fm = make_file_manager(options.install_dir)
@@ -1356,9 +1359,14 @@ def make_file_manager(install_dir: str) -> FileManager:
             cpu_fm=cpu_fm)
 
     if options.output_dependencies:
-        cpu_fm.write_outputs(options.output_dependencies)
-        core_fm.write_outputs(f"{options.output_dependencies}-core")
-        cuda_fm.write_outputs(f"{options.output_dependencies}-cuda")
+        depfile_path = pathlib.Path(options.output_dependencies).resolve()
+        depfile_name = depfile_path.name
+        depfile_stem = depfile_path.stem
+
+        for fm, prefix in [(cpu_fm, ""), (core_fm, "core_"), (cuda_fm, "cuda_")]:
+            varname = prefix + depfile_stem
+            path = depfile_path.parent / (prefix + depfile_name)
+            fm.write_outputs(varname, str(path))
 
 
 if __name__ == '__main__':
diff --git a/tools/codegen/utils.py b/tools/codegen/utils.py
index c96b6cdd6c21dd..406ae0d2ce897c 100644
--- a/tools/codegen/utils.py
+++ b/tools/codegen/utils.py
@@ -224,9 +224,9 @@ def merge_env(into: Dict[str, List[str]], from_: Dict[str, List[str]]) -> None:
         self.filenames.discard(
             f"{self.install_dir}/{base_filename}Everything{extension}")
 
-    def write_outputs(self, filename: str) -> None:
+    def write_outputs(self, variable_name: str, filename: str) -> None:
         """Write a file containing the list of all outputs which are
         generated by this script."""
-        self._write_if_changed(
-            filename,
-            ''.join(name + ";" for name in sorted(self.filenames)))
+        content = 'set({}\n    {})'.format(
+            variable_name, '\n    '.join('"' + name + '"' for name in sorted(self.filenames)))
+        self._write_if_changed(filename, content)