diff --git a/httpx/_transports/mock.py b/httpx/_transports/mock.py
index 8c418f59e0..d521838977 100644
--- a/httpx/_transports/mock.py
+++ b/httpx/_transports/mock.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import typing
+from datetime import timedelta
 
 from .._models import Request, Response
 from .base import AsyncBaseTransport, BaseTransport
@@ -13,8 +14,11 @@
 
 
 class MockTransport(AsyncBaseTransport, BaseTransport):
-    def __init__(self, handler: SyncHandler | AsyncHandler) -> None:
+    def __init__(
+        self, handler: SyncHandler | AsyncHandler, delay: timedelta = timedelta(0)
+    ) -> None:
         self.handler = handler
+        self.delay = delay
 
     def handle_request(
         self,
@@ -24,6 +28,8 @@ def handle_request(
         response = self.handler(request)
         if not isinstance(response, Response):  # pragma: no cover
             raise TypeError("Cannot use an async handler in a sync Client")
+
+        self._apply_elapsed(response)
         return response
 
     async def handle_async_request(
@@ -40,4 +46,14 @@ async def handle_async_request(
         if not isinstance(response, Response):
             response = await response
 
+        self._apply_elapsed(response)
         return response
+
+    def _apply_elapsed(self, response: Response) -> None:
+        # If the handler already set `response._elapsed`, it is preserved.
+        # If a delay was provided to MockTransport, `.elapsed` is set to that duration.
+        # If no delay is provided, `.elapsed` is explicitly set to None.
+        if hasattr(response, "_elapsed"):
+            return
+
+        response._elapsed = self.delay
diff --git a/tests/client/test_client.py b/tests/client/test_client.py
index 657839018a..a7fd670a08 100644
--- a/tests/client/test_client.py
+++ b/tests/client/test_client.py
@@ -460,3 +460,41 @@ def cp1252_but_no_content_type(request):
         assert response.reason_phrase == "OK"
         assert response.encoding == "ISO-8859-1"
         assert response.text == text
+
+
+def test_mocktransport_preserves_handler_elapsed():
+    def handler(request):
+        r = httpx.Response(200)
+        r.elapsed = timedelta(seconds=1)
+        return r
+
+    transport = httpx.MockTransport(handler, delay=timedelta(seconds=0.5))
+    client = httpx.Client(transport=transport)
+
+    response = client.get("https://example.com")
+
+    assert response.elapsed == timedelta(seconds=1)
+
+
+def test_mocktransport_sets_elapsed_to_delay():
+    def handler(request):
+        return httpx.Response(200)
+
+    transport = httpx.MockTransport(handler, delay=timedelta(seconds=0.5))
+    client = httpx.Client(transport=transport)
+
+    response = client.get("https://example.com")
+
+    assert response.elapsed == timedelta(seconds=0.5)
+
+
+def test_mocktransport_sets_elapsed_none_when_no_delay():
+    def handler(request):
+        return httpx.Response(200)
+
+    transport = httpx.MockTransport(handler)
+    client = httpx.Client(transport=transport)
+
+    response = client.get("https://example.com")
+
+    assert response.elapsed == timedelta(0)