diff --git a/libs/langchain/langchain/schema/runnable/base.py b/libs/langchain/langchain/schema/runnable/base.py
index 0a36467f3f8..1b3061a259a 100644
--- a/libs/langchain/langchain/schema/runnable/base.py
+++ b/libs/langchain/langchain/schema/runnable/base.py
@@ -54,6 +54,7 @@ from langchain.schema.runnable.config import (
     get_callback_manager_for_config,
     get_config_list,
     get_executor_for_config,
+    merge_configs,
     patch_config,
 )
 from langchain.schema.runnable.utils import (
@@ -564,7 +565,12 @@ class Runnable(Generic[Input, Output], ABC):
         Bind config to a Runnable, returning a new Runnable.
         """
         return RunnableBinding(
-            bound=self, config={**(config or {}), **kwargs}, kwargs={}
+            bound=self,
+            config=cast(
+                RunnableConfig,
+                {**(config or {}), **kwargs},
+            ),  # type: ignore[misc]
+            kwargs={},
         )
 
     def with_retry(
@@ -2291,7 +2297,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
 
     kwargs: Mapping[str, Any]
 
-    config: Mapping[str, Any] = Field(default_factory=dict)
+    config: RunnableConfig = Field(default_factory=dict)
 
     class Config:
         arbitrary_types_allowed = True
@@ -2301,7 +2307,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
         *,
         bound: Runnable[Input, Output],
         kwargs: Mapping[str, Any],
-        config: Optional[Mapping[str, Any]] = None,
+        config: Optional[RunnableConfig] = None,
         **other_kwargs: Any,
     ) -> None:
         config = config or {}
@@ -2347,22 +2353,6 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     def get_lc_namespace(cls) -> List[str]:
         return cls.__module__.split(".")[:-1]
 
-    def _merge_config(self, config: Optional[RunnableConfig]) -> RunnableConfig:
-        copy = cast(RunnableConfig, dict(self.config))
-        if config:
-            for key in config:
-                if key == "metadata":
-                    copy[key] = {**copy.get(key, {}), **config[key]}  # type: ignore
-                elif key == "tags":
-                    copy[key] = (copy.get(key) or []) + config[key]  # type: ignore
-                elif key == "configurable":
-                    copy[key] = {**copy.get(key, {}), **config[key]}  # type: ignore
-                else:
-                    # Even though the keys aren't literals this is correct
-                    # because both dicts are same type
-                    copy[key] = config[key] or copy.get(key)  # type: ignore
-        return copy
-
     def bind(self, **kwargs: Any) -> Runnable[Input, Output]:
         return self.__class__(
             bound=self.bound, config=self.config, kwargs={**self.kwargs, **kwargs}
@@ -2377,7 +2367,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
         return self.__class__(
             bound=self.bound,
             kwargs=self.kwargs,
-            config={**self.config, **(config or {}), **kwargs},
+            config=cast(RunnableConfig, {**self.config, **(config or {}), **kwargs}),
         )
 
     def with_retry(self, **kwargs: Any) -> Runnable[Input, Output]:
@@ -2395,7 +2385,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     ) -> Output:
         return self.bound.invoke(
             input,
-            self._merge_config(config),
+            merge_configs(self.config, config),
             **{**self.kwargs, **kwargs},
         )
 
@@ -2407,7 +2397,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     ) -> Output:
         return await self.bound.ainvoke(
             input,
-            self._merge_config(config),
+            merge_configs(self.config, config),
             **{**self.kwargs, **kwargs},
         )
 
@@ -2421,11 +2411,12 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     ) -> List[Output]:
         if isinstance(config, list):
             configs = cast(
-                List[RunnableConfig], [self._merge_config(conf) for conf in config]
+                List[RunnableConfig],
+                [merge_configs(self.config, conf) for conf in config],
             )
         else:
             configs = [
-                patch_config(self._merge_config(config), copy_locals=True)
+                patch_config(merge_configs(self.config, config), copy_locals=True)
                 for _ in range(len(inputs))
             ]
         return self.bound.batch(
@@ -2445,11 +2436,12 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     ) -> List[Output]:
         if isinstance(config, list):
             configs = cast(
-                List[RunnableConfig], [self._merge_config(conf) for conf in config]
+                List[RunnableConfig],
+                [merge_configs(self.config, conf) for conf in config],
             )
         else:
             configs = [
-                patch_config(self._merge_config(config), copy_locals=True)
+                patch_config(merge_configs(self.config, config), copy_locals=True)
                 for _ in range(len(inputs))
             ]
         return await self.bound.abatch(
@@ -2467,7 +2459,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     ) -> Iterator[Output]:
         yield from self.bound.stream(
             input,
-            self._merge_config(config),
+            merge_configs(self.config, config),
             **{**self.kwargs, **kwargs},
         )
 
@@ -2479,7 +2471,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     ) -> AsyncIterator[Output]:
         async for item in self.bound.astream(
             input,
-            self._merge_config(config),
+            merge_configs(self.config, config),
             **{**self.kwargs, **kwargs},
         ):
             yield item
@@ -2492,7 +2484,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     ) -> Iterator[Output]:
         yield from self.bound.transform(
             input,
-            self._merge_config(config),
+            merge_configs(self.config, config),
             **{**self.kwargs, **kwargs},
         )
 
@@ -2504,7 +2496,7 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
     ) -> AsyncIterator[Output]:
         async for item in self.bound.atransform(
             input,
-            self._merge_config(config),
+            merge_configs(self.config, config),
             **{**self.kwargs, **kwargs},
         ):
             yield item
diff --git a/libs/langchain/langchain/schema/runnable/config.py b/libs/langchain/langchain/schema/runnable/config.py
index 71eb7428e06..1b720fb5b6e 100644
--- a/libs/langchain/langchain/schema/runnable/config.py
+++ b/libs/langchain/langchain/schema/runnable/config.py
@@ -157,6 +157,31 @@ def patch_config(
     return config
 
 
+def merge_configs(*configs: Optional[RunnableConfig]) -> RunnableConfig:
+    base: RunnableConfig = {}
+    # Even though the keys aren't literals this is correct
+    # because both dicts are same type
+    for config in (c for c in configs if c is not None):
+        for key in config:
+            if key == "metadata":
+                base[key] = {  # type: ignore
+                    **base.get(key, {}),  # type: ignore
+                    **(config.get(key) or {}),  # type: ignore
+                }
+            elif key == "tags":
+                base[key] = list(  # type: ignore
+                    set(base.get(key, []) + (config.get(key) or [])),  # type: ignore
+                )
+            elif key == "configurable":
+                base[key] = {  # type: ignore
+                    **base.get(key, {}),  # type: ignore
+                    **(config.get(key) or {}),  # type: ignore
+                }
+            else:
+                base[key] = config[key] or base.get(key)  # type: ignore
+    return base
+
+
 def call_func_with_variable_args(
     func: Union[
         Callable[[Input], Output],