diff --git a/stdlib/subprocess.pyi b/stdlib/subprocess.pyi
index 66e3e23e8..2666fef87 100644
--- a/stdlib/subprocess.pyi
+++ b/stdlib/subprocess.pyi
@@ -101,7 +101,209 @@ class CompletedProcess(Generic[_T]):
     if sys.version_info >= (3, 9):
         def __class_getitem__(cls, item: Any) -> GenericAlias: ...
 
-if sys.version_info >= (3, 9):
+if sys.version_info >= (3, 10):
+    # 3.10 adds "pipesize" argument
+    @overload
+    def run(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stdout: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        capture_output: bool = ...,
+        check: bool = ...,
+        encoding: str | None = ...,
+        errors: str | None = ...,
+        input: str | None = ...,
+        text: Literal[True],
+        timeout: float | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> CompletedProcess[str]: ...
+    @overload
+    def run(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stdout: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        capture_output: bool = ...,
+        check: bool = ...,
+        encoding: str,
+        errors: str | None = ...,
+        input: str | None = ...,
+        text: bool | None = ...,
+        timeout: float | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> CompletedProcess[str]: ...
+    @overload
+    def run(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stdout: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        capture_output: bool = ...,
+        check: bool = ...,
+        encoding: str | None = ...,
+        errors: str,
+        input: str | None = ...,
+        text: bool | None = ...,
+        timeout: float | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> CompletedProcess[str]: ...
+    @overload
+    def run(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stdout: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        *,
+        universal_newlines: Literal[True],
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        # where the *real* keyword only args start
+        capture_output: bool = ...,
+        check: bool = ...,
+        encoding: str | None = ...,
+        errors: str | None = ...,
+        input: str | None = ...,
+        text: bool | None = ...,
+        timeout: float | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> CompletedProcess[str]: ...
+    @overload
+    def run(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stdout: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: Literal[False] = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        capture_output: bool = ...,
+        check: bool = ...,
+        encoding: None = ...,
+        errors: None = ...,
+        input: bytes | None = ...,
+        text: Literal[None, False] = ...,
+        timeout: float | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> CompletedProcess[bytes]: ...
+    @overload
+    def run(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stdout: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        capture_output: bool = ...,
+        check: bool = ...,
+        encoding: str | None = ...,
+        errors: str | None = ...,
+        input: _TXT | None = ...,
+        text: bool | None = ...,
+        timeout: float | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> CompletedProcess[Any]: ...
+
+elif sys.version_info >= (3, 9):
     # 3.9 adds arguments "user", "group", "extra_groups" and "umask"
     @overload
     def run(
@@ -604,7 +806,37 @@ else:
     ) -> CompletedProcess[Any]: ...
 
 # Same args as Popen.__init__
-if sys.version_info >= (3, 9):
+if sys.version_info >= (3, 10):
+    # 3.10 adds "pipesize" argument
+    def call(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stdout: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        timeout: float | None = ...,
+        text: bool | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> int: ...
+
+elif sys.version_info >= (3, 9):
     # 3.9 adds arguments "user", "group", "extra_groups" and "umask"
     def call(
         args: _CMD,
@@ -682,7 +914,37 @@ else:
     ) -> int: ...
 
 # Same args as Popen.__init__
-if sys.version_info >= (3, 9):
+if sys.version_info >= (3, 10):
+    # 3.10 adds "pipesize" argument
+    def check_call(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath = ...,
+        stdin: _FILE = ...,
+        stdout: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        timeout: float | None = ...,
+        *,
+        text: bool | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> int: ...
+
+elif sys.version_info >= (3, 9):
     # 3.9 adds arguments "user", "group", "extra_groups" and "umask"
     def check_call(
         args: _CMD,
@@ -758,7 +1020,191 @@ else:
         timeout: float | None = ...,
     ) -> int: ...
 
-if sys.version_info >= (3, 9):
+if sys.version_info >= (3, 10):
+    # 3.10 adds "pipesize" argument
+    @overload
+    def check_output(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        timeout: float | None = ...,
+        input: _TXT | None = ...,
+        encoding: str | None = ...,
+        errors: str | None = ...,
+        text: Literal[True],
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> str: ...
+    @overload
+    def check_output(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        timeout: float | None = ...,
+        input: _TXT | None = ...,
+        encoding: str,
+        errors: str | None = ...,
+        text: bool | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> str: ...
+    @overload
+    def check_output(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        timeout: float | None = ...,
+        input: _TXT | None = ...,
+        encoding: str | None = ...,
+        errors: str,
+        text: bool | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> str: ...
+    @overload
+    def check_output(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        *,
+        universal_newlines: Literal[True],
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        # where the real keyword only ones start
+        timeout: float | None = ...,
+        input: _TXT | None = ...,
+        encoding: str | None = ...,
+        errors: str | None = ...,
+        text: bool | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> str: ...
+    @overload
+    def check_output(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: Literal[False] = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        timeout: float | None = ...,
+        input: _TXT | None = ...,
+        encoding: None = ...,
+        errors: None = ...,
+        text: Literal[None, False] = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> bytes: ...
+    @overload
+    def check_output(
+        args: _CMD,
+        bufsize: int = ...,
+        executable: StrOrBytesPath | None = ...,
+        stdin: _FILE = ...,
+        stderr: _FILE = ...,
+        preexec_fn: Callable[[], Any] | None = ...,
+        close_fds: bool = ...,
+        shell: bool = ...,
+        cwd: StrOrBytesPath | None = ...,
+        env: _ENV | None = ...,
+        universal_newlines: bool = ...,
+        startupinfo: Any = ...,
+        creationflags: int = ...,
+        restore_signals: bool = ...,
+        start_new_session: bool = ...,
+        pass_fds: Any = ...,
+        *,
+        timeout: float | None = ...,
+        input: _TXT | None = ...,
+        encoding: str | None = ...,
+        errors: str | None = ...,
+        text: bool | None = ...,
+        user: str | int | None = ...,
+        group: str | int | None = ...,
+        extra_groups: Iterable[str | int] | None = ...,
+        umask: int = ...,
+        pipesize: int = ...,
+    ) -> Any: ...  # morally: -> _TXT
+
+elif sys.version_info >= (3, 9):
     # 3.9 adds arguments "user", "group", "extra_groups" and "umask"
     @overload
     def check_output(