--- a/pyproject.toml
+++ b/pyproject.toml
@@ -8,7 +8,6 @@ exclude = '''
 ( __pycache__
 | ^/.tox
 | ^/versioneer.py
-| ^/src/debugpy/_vendored
 | ^/src/debugpy/_version.py
 )
 '''
--- a/setup.py
+++ b/setup.py
@@ -18,12 +18,10 @@ del sys.path[0]
 
 sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), "src"))
 import debugpy
-import debugpy._vendored
 
 del sys.path[0]
 
 
-PYDEVD_ROOT = debugpy._vendored.project_root("pydevd")
 DEBUGBY_ROOT = os.path.dirname(os.path.abspath(debugpy.__file__))
 
 
@@ -33,27 +31,6 @@ def get_buildplatform():
     return None
 
 
-def cython_build():
-    print("Compiling extension modules (set SKIP_CYTHON_BUILD=1 to omit)")
-    subprocess.call(
-        [
-            sys.executable,
-            os.path.join(PYDEVD_ROOT, "setup_pydevd_cython.py"),
-            "build_ext",
-            "-i",
-        ]
-    )
-
-
-def iter_vendored_files():
-    # Add pydevd files as data files for this package. They are not
-    # treated as a package of their own, because we don't actually
-    # want to provide pydevd - just use our own copy internally.
-    for project in debugpy._vendored.list_all():
-        for filename in debugpy._vendored.iter_packaging_files(project):
-            yield filename
-
-
 # bdist_wheel determines whether the package is pure or not based on ext_modules.
 # However, all pydevd native modules are prebuilt and packaged as data, so they
 # should not be in the list.
@@ -133,8 +110,6 @@ with open("DESCRIPTION.md", "r") as fh:
 
 
 if __name__ == "__main__":
-    if not os.getenv("SKIP_CYTHON_BUILD"):
-        cython_build()
 
     extras = {}
     platforms = get_buildplatform()
@@ -179,11 +154,9 @@ if __name__ == "__main__":
             "debugpy.common",
             "debugpy.launcher",
             "debugpy.server",
-            "debugpy._vendored",
         ],
         package_data={
             "debugpy": ["ThirdPartyNotices.txt"],
-            "debugpy._vendored": list(iter_vendored_files()),
         },
         ext_modules=ExtModules(),
         has_ext_modules=lambda: True,
--- a/src/debugpy/server/__init__.py
+++ b/src/debugpy/server/__init__.py
@@ -1,7 +1,3 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License. See LICENSE in the project root
 # for license information.
-
-# "force_pydevd" must be imported first to ensure (via side effects)
-# that the debugpy-vendored copy of pydevd gets used.
-import debugpy._vendored.force_pydevd  # noqa
--- a/src/debugpy/server/attach_pid_injected.py
+++ b/src/debugpy/server/attach_pid_injected.py
@@ -31,7 +31,6 @@ def attach(setup):
                 pydevd_attach_to_process_path = os.path.join(
                     _debugpy_dir,
                     "debugpy",
-                    "_vendored",
                     "pydevd",
                     "pydevd_attach_to_process",
                 )