diff --git a/third_party/2and3/attr/__init__.pyi b/third_party/2and3/attr/__init__.pyi
new file mode 100644
index 000000000000..903c6135043a
--- /dev/null
+++ b/third_party/2and3/attr/__init__.pyi
@@ -0,0 +1,334 @@
+from typing import Any, Callable, Dict, Generic, List, Optional, Sequence, Mapping, Tuple, Type, TypeVar, Union, overload
+# `import X as X` is required to make these public
+from . import exceptions as exceptions
+from . import filters as filters
+from . import converters as converters
+from . import validators as validators
+
+_T = TypeVar('_T')
+_C = TypeVar('_C', bound=type)
+
+_ValidatorType = Callable[[Any, Attribute, _T], Any]
+_ConverterType = Callable[[Any], _T]
+_FilterType = Callable[[Attribute, Any], bool]
+# FIXME: in reality, if multiple validators are passed they must be in a list or tuple,
+# but those are invariant and so would prevent subtypes of _ValidatorType from working
+# when passed in a list or tuple.
+_ValidatorArgType = Union[_ValidatorType[_T], Sequence[_ValidatorType[_T]]]
+
+# _make --
+
+NOTHING: object
+
+# NOTE: Factory lies about its return type to make this possible: `x: List[int] = Factory(list)`
+def Factory(factory: Union[Callable[[], _T], Callable[[Any], _T]], takes_self: bool = ...) -> _T: ...
+
+class Attribute(Generic[_T]):
+ name: str
+ default: Optional[_T]
+ validator: Optional[_ValidatorType[_T]]
+ repr: bool
+ cmp: bool
+ hash: Optional[bool]
+ init: bool
+ converter: Optional[_ConverterType[_T]]
+ metadata: Dict[Any, Any]
+ type: Optional[Type[_T]]
+ def __lt__(self, x: Attribute) -> bool: ...
+ def __le__(self, x: Attribute) -> bool: ...
+ def __gt__(self, x: Attribute) -> bool: ...
+ def __ge__(self, x: Attribute) -> bool: ...
+
+
+# NOTE: We had several choices for the annotation to use for type arg:
+# 1) Type[_T]
+# - Pros: works in PyCharm without plugin support
+# - Cons: produces less informative error in the case of conflicting TypeVars
+# e.g. `attr.ib(default='bad', type=int)`
+# 2) Callable[..., _T]
+# - Pros: more informative errors than #1
+# - Cons: validator tests results in confusing error.
+# e.g. `attr.ib(type=int, validator=validate_str)`
+# 3) type (and do all of the work in the mypy plugin)
+# - Pros: in mypy, the behavior of type argument is exactly the same as with
+# annotations.
+# - Cons: completely disables type inspections in PyCharm when using the
+# type arg.
+# We chose option #1 until either PyCharm adds support for attrs, or python 2
+# reaches EOL.
+
+# NOTE: If you update these, update `ib` and `attr` below.
+
+# `attr` lies about its return type to make the following possible:
+# attr() -> Any
+# attr(8) -> int
+# attr(validator=<some callable>) -> Whatever the callable expects.
+# This makes this type of assignments possible:
+# x: int = attr(8)
+
+# 1st form catches _T set.
+@overload
+def attrib(default: Optional[_T] = ...,
+ validator: Optional[_ValidatorArgType[_T]] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: Optional[Type[_T]] = ...,
+ converter: Optional[_ConverterType[_T]] = ...) -> _T: ...
+# 2nd form no _T , so returns Any.
+@overload
+def attrib(default: None = ...,
+ validator: None = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: None = ...,
+ converter: None = ...) -> Any: ...
+# 3rd form covers non-Type: e.g. forward references (str), Any
+@overload
+def attrib(default: Optional[_T] = ...,
+ validator: Optional[_ValidatorArgType[_T]] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: object = ...,
+ converter: Optional[_ConverterType[_T]] = ...) -> Any: ...
+
+
+# NOTE: If you update these, update `s` and `attributes` below.
+@overload
+def attrs(maybe_cls: _C,
+ these: Optional[Dict[str, Any]] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...,
+ auto_attribs: bool = ...) -> _C: ...
+@overload
+def attrs(maybe_cls: None = ...,
+ these: Optional[Dict[str, Any]] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...,
+ auto_attribs: bool = ...) -> Callable[[_C], _C]: ...
+
+
+# TODO: add support for returning NamedTuple from the mypy plugin
+class _Fields(Tuple[Attribute, ...]):
+ def __getattr__(self, name: str) -> Attribute: ...
+
+def fields(cls: type) -> _Fields: ...
+def validate(inst: Any) -> None: ...
+
+# TODO: add support for returning a proper attrs class from the mypy plugin
+# we use Any instead of _CountingAttr so that e.g. `make_class('Foo', [attr.ib()])` is valid
+def make_class(name: str,
+ attrs: Union[List[str], Tuple[str, ...], Dict[str, Any]],
+ bases: Tuple[type, ...] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...,
+ auto_attribs: bool = ...) -> type: ...
+
+# _funcs --
+
+# TODO: add support for returning TypedDict from the mypy plugin
+# FIXME: asdict/astuple do not honor their factory args. waiting on one of these:
+# https://github.com/python/mypy/issues/4236
+# https://github.com/python/typing/issues/253
+def asdict(inst: Any,
+ recurse: bool = ...,
+ filter: Optional[_FilterType] = ...,
+ dict_factory: Type[Mapping[Any, Any]] = ...,
+ retain_collection_types: bool = ...) -> Dict[str, Any]: ...
+# TODO: add support for returning NamedTuple from the mypy plugin
+def astuple(inst: Any,
+ recurse: bool = ...,
+ filter: Optional[_FilterType] = ...,
+ tuple_factory: Type[Sequence] = ...,
+ retain_collection_types: bool = ...) -> Tuple[Any, ...]: ...
+def has(cls: type) -> bool: ...
+def assoc(inst: _T, **changes: Any) -> _T: ...
+def evolve(inst: _T, **changes: Any) -> _T: ...
+
+# _config --
+
+def set_run_validators(run: bool) -> None: ...
+def get_run_validators() -> bool: ...
+
+
+# aliases --
+
+# FIXME: there is a bug in PyCharm with creating aliases to overloads.
+# Use the aliases instead of the duplicated overloads when the bug is fixed:
+# https://youtrack.jetbrains.com/issue/PY-27788
+
+# s = attributes = attrs
+# ib = attr = attrib
+# dataclass = attrs # Technically, partial(attrs, auto_attribs=True) ;)
+
+
+@overload
+def ib(default: Optional[_T] = ...,
+ validator: Optional[_ValidatorArgType[_T]] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: Optional[Type[_T]] = ...,
+ converter: Optional[_ConverterType[_T]] = ...) -> _T: ...
+@overload
+def ib(default: None = ...,
+ validator: None = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: None = ...,
+ converter: None = ...) -> Any: ...
+@overload
+def ib(default: Optional[_T] = ...,
+ validator: Optional[_ValidatorArgType[_T]] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: object = ...,
+ converter: Optional[_ConverterType[_T]] = ...) -> Any: ...
+
+@overload
+def attr(default: Optional[_T] = ...,
+ validator: Optional[_ValidatorArgType[_T]] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: Optional[Type[_T]] = ...,
+ converter: Optional[_ConverterType[_T]] = ...) -> _T: ...
+@overload
+def attr(default: None = ...,
+ validator: None = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: None = ...,
+ converter: None = ...) -> Any: ...
+@overload
+def attr(default: Optional[_T] = ...,
+ validator: Optional[_ValidatorArgType[_T]] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ convert: Optional[_ConverterType[_T]] = ...,
+ metadata: Optional[Mapping[Any, Any]] = ...,
+ type: object = ...,
+ converter: Optional[_ConverterType[_T]] = ...) -> Any: ...
+
+@overload
+def attributes(maybe_cls: _C,
+ these: Optional[Dict[str, Any]] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...,
+ auto_attribs: bool = ...) -> _C: ...
+@overload
+def attributes(maybe_cls: None = ...,
+ these: Optional[Dict[str, Any]] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...,
+ auto_attribs: bool = ...) -> Callable[[_C], _C]: ...
+
+@overload
+def s(maybe_cls: _C,
+ these: Optional[Dict[str, Any]] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...,
+ auto_attribs: bool = ...) -> _C: ...
+@overload
+def s(maybe_cls: None = ...,
+ these: Optional[Dict[str, Any]] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...,
+ auto_attribs: bool = ...) -> Callable[[_C], _C]: ...
+
+# same as above, but with auto_attrib=True
+@overload
+def dataclass(maybe_cls: _C,
+ these: Optional[Dict[str, Any]] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...) -> _C: ...
+@overload
+def dataclass(maybe_cls: None = ...,
+ these: Optional[Dict[str, Any]] = ...,
+ repr_ns: Optional[str] = ...,
+ repr: bool = ...,
+ cmp: bool = ...,
+ hash: Optional[bool] = ...,
+ init: bool = ...,
+ slots: bool = ...,
+ frozen: bool = ...,
+ str: bool = ...) -> Callable[[_C], _C]: ...
diff --git a/third_party/2and3/attr/converters.pyi b/third_party/2and3/attr/converters.pyi
new file mode 100644
index 000000000000..9e31677e79c3
--- /dev/null
+++ b/third_party/2and3/attr/converters.pyi
@@ -0,0 +1,6 @@
+from typing import TypeVar, Optional
+from . import _ConverterType
+
+_T = TypeVar('_T')
+
+def optional(converter: _ConverterType[_T]) -> _ConverterType[Optional[_T]]: ...
diff --git a/third_party/2and3/attr/exceptions.pyi b/third_party/2and3/attr/exceptions.pyi
new file mode 100644
index 000000000000..4a2904fc25b1
--- /dev/null
+++ b/third_party/2and3/attr/exceptions.pyi
@@ -0,0 +1,6 @@
+class FrozenInstanceError(AttributeError):
+ msg: str = ...
+class AttrsAttributeNotFoundError(ValueError): ...
+class NotAnAttrsClassError(ValueError): ...
+class DefaultAlreadySetError(RuntimeError): ...
+class UnannotatedAttributeError(RuntimeError): ...
diff --git a/third_party/2and3/attr/filters.pyi b/third_party/2and3/attr/filters.pyi
new file mode 100644
index 000000000000..a618140c2d1b
--- /dev/null
+++ b/third_party/2and3/attr/filters.pyi
@@ -0,0 +1,5 @@
+from typing import Union
+from . import Attribute, _FilterType
+
+def include(*what: Union[type, Attribute]) -> _FilterType: ...
+def exclude(*what: Union[type, Attribute]) -> _FilterType: ...
diff --git a/third_party/2and3/attr/validators.pyi b/third_party/2and3/attr/validators.pyi
new file mode 100644
index 000000000000..477bac91c39b
--- /dev/null
+++ b/third_party/2and3/attr/validators.pyi
@@ -0,0 +1,10 @@
+from typing import Container, List, Union, TypeVar, Type, Any, Optional
+from . import _ValidatorType
+
+_T = TypeVar('_T')
+
+def instance_of(type: Type[_T]) -> _ValidatorType[_T]: ...
+def provides(interface: Any) -> _ValidatorType[Any]: ...
+def optional(validator: Union[_ValidatorType[_T], List[_ValidatorType[_T]]]) -> _ValidatorType[Optional[_T]]: ...
+def in_(options: Container[_T]) -> _ValidatorType[_T]: ...
+def and_(*validators: _ValidatorType[_T]) -> _ValidatorType[_T]: ...