diff --git a/mypy/build.py b/mypy/build.py
index c6c44fd6ead8..8391c34e48ec 100644
--- a/mypy/build.py
+++ b/mypy/build.py
@@ -1967,7 +1967,9 @@ def compute_dependencies(self) -> None:
         dependencies = []
         priorities = {}  # type: Dict[str, int]  # id -> priority
         dep_line_map = {}  # type: Dict[str, int]  # id -> line
-        for pri, id, line in manager.all_imported_modules_in_file(self.tree):
+        dep_entries = (manager.all_imported_modules_in_file(self.tree) +
+                       self.manager.plugin.get_additional_deps(self.tree))
+        for pri, id, line in dep_entries:
             priorities[id] = min(pri, priorities.get(id, PRI_ALL))
             if id == self.id:
                 continue
diff --git a/mypy/interpreted_plugin.py b/mypy/interpreted_plugin.py
index e95fbe1e3260..981e8eb350d6 100644
--- a/mypy/interpreted_plugin.py
+++ b/mypy/interpreted_plugin.py
@@ -1,6 +1,6 @@
 """Hack for handling non-mypyc compiled plugins with a mypyc-compiled mypy"""
 
-from typing import Optional, Callable, Any, Dict
+from typing import Optional, Callable, Any, Dict, List, Tuple
 from mypy.options import Options
 from mypy.types import Type, CallableType
 from mypy.nodes import SymbolTableNode, MypyFile
@@ -39,6 +39,9 @@ def lookup_fully_qualified(self, fullname: str) -> Optional[SymbolTableNode]:
         assert self._modules is not None
         return lookup_fully_qualified(fullname, self._modules)
 
+    def get_additional_deps(self, file: MypyFile) -> List[Tuple[int, str, int]]:
+        return []
+
     def get_type_analyze_hook(self, fullname: str
                               ) -> Optional[Callable[['mypy.plugin.AnalyzeTypeContext'], Type]]:
         return None
diff --git a/mypy/plugin.py b/mypy/plugin.py
index ca66c47999dd..1e46b3c3f52f 100644
--- a/mypy/plugin.py
+++ b/mypy/plugin.py
@@ -371,6 +371,23 @@ def lookup_fully_qualified(self, fullname: str) -> Optional[SymbolTableNode]:
         assert self._modules is not None
         return lookup_fully_qualified(fullname, self._modules)
 
+    def get_additional_deps(self, file: MypyFile) -> List[Tuple[int, str, int]]:
+        """Customize dependencies for a module.
+
+        This hook allows adding in new dependencies for a module. It
+        is called after parsing a file but before analysis. This can
+        be useful if a library has dependencies that are dynamic based
+        on configuration information, for example.
+
+        Returns a list of (priority, module name, line number) tuples.
+
+        The line number can be -1 when there is not a known real line number.
+
+        Priorities are defined in mypy.build (but maybe shouldn't be).
+        10 is a good choice for priority.
+        """
+        return []
+
     def get_type_analyze_hook(self, fullname: str
                               ) -> Optional[Callable[[AnalyzeTypeContext], Type]]:
         """Customize behaviour of the type analyzer for given full names.
@@ -395,7 +412,7 @@ def get_function_hook(self, fullname: str
         """Adjust the return type of a function call.
 
         This method is called after type checking a call. Plugin may adjust the return
-        type inferred by mypy, and/or emmit some error messages. Note, this hook is also
+        type inferred by mypy, and/or emit some error messages. Note, this hook is also
         called for class instantiation calls, so that in this example:
 
             from lib import Class, do_stuff
@@ -561,6 +578,9 @@ def set_modules(self, modules: Dict[str, MypyFile]) -> None:
     def lookup_fully_qualified(self, fullname: str) -> Optional[SymbolTableNode]:
         return self.plugin.lookup_fully_qualified(fullname)
 
+    def get_additional_deps(self, file: MypyFile) -> List[Tuple[int, str, int]]:
+        return self.plugin.get_additional_deps(file)
+
     def get_type_analyze_hook(self, fullname: str
                               ) -> Optional[Callable[[AnalyzeTypeContext], Type]]:
         return self.plugin.get_type_analyze_hook(fullname)
@@ -626,6 +646,12 @@ def set_modules(self, modules: Dict[str, MypyFile]) -> None:
         for plugin in self._plugins:
             plugin.set_modules(modules)
 
+    def get_additional_deps(self, file: MypyFile) -> List[Tuple[int, str, int]]:
+        deps = []
+        for plugin in self._plugins:
+            deps.extend(plugin.get_additional_deps(file))
+        return deps
+
     def get_type_analyze_hook(self, fullname: str
                               ) -> Optional[Callable[[AnalyzeTypeContext], Type]]:
         return self._find_hook(lambda plugin: plugin.get_type_analyze_hook(fullname))
diff --git a/test-data/unit/check-custom-plugin.test b/test-data/unit/check-custom-plugin.test
index b810b8ba46b2..44ac81cbc865 100644
--- a/test-data/unit/check-custom-plugin.test
+++ b/test-data/unit/check-custom-plugin.test
@@ -71,7 +71,6 @@ tmp/mypy.ini:2: error: Can't find plugin 'tmp/missing.py'
 plugins=missing
 [out]
 tmp/mypy.ini:2: error: Error importing plugin 'missing'
---' (work around syntax highlighting)
 
 [case testMultipleSectionsDefinePlugin]
 # flags: --config-file tmp/mypy.ini
@@ -585,3 +584,16 @@ reveal_type(instance(2))  # E: Revealed type is 'builtins.float*'
 [file mypy.ini]
 [[mypy]
 plugins=<ROOT>/test-data/unit/plugins/callable_instance.py
+
+[case testPluginDependencies]
+# flags: --config-file tmp/mypy.ini
+
+# The top level file here doesn't do anything, but the plugin should add
+# a dependency on err that will cause err to be processed and an error reported.
+
+[file err.py]
+1 + 'lol'  # E: Unsupported operand types for + ("int" and "str")
+
+[file mypy.ini]
+[[mypy]
+plugins=<ROOT>/test-data/unit/plugins/depshook.py
diff --git a/test-data/unit/plugins/depshook.py b/test-data/unit/plugins/depshook.py
new file mode 100644
index 000000000000..99a6fd14dc02
--- /dev/null
+++ b/test-data/unit/plugins/depshook.py
@@ -0,0 +1,15 @@
+from typing import Optional, Callable, List, Tuple
+
+from mypy.plugin import Plugin
+from mypy.nodes import MypyFile
+
+
+class DepsPlugin(Plugin):
+    def get_additional_deps(self, file: MypyFile) -> List[Tuple[int, str, int]]:
+        if file.fullname() == '__main__':
+            return [(10, 'err', -1)]
+        return []
+
+
+def plugin(version):
+    return DepsPlugin