diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index d3738cfa3e78..48dd69155cea 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -1769,6 +1769,13 @@ fn document_type_layout(w: &mut Buffer, cx: &Context<'_>, ty_def_id: DefId) {
                  the type was too big.</p>"
             );
         }
+        Err(LayoutError::NormalizationFailure(_, _)) => {
+            writeln!(
+                w,
+                "<p><strong>Note:</strong> Encountered an error during type layout; \
+                the type was not normalizable.</p>"
+            )
+        }
     }
 
     writeln!(w, "</div>");
diff --git a/src/test/ui/associated-types/issue-85103.rs b/src/test/ui/associated-types/issue-85103.rs
new file mode 100644
index 000000000000..c5e13856178d
--- /dev/null
+++ b/src/test/ui/associated-types/issue-85103.rs
@@ -0,0 +1,9 @@
+#![feature(rustc_attrs)]
+
+use std::borrow::Cow;
+
+#[rustc_layout(debug)]
+type Edges<'a, E> = Cow<'a, [E]>;
+//~^ ERROR layout error: NormalizationFailure
+
+fn main() {}
diff --git a/src/test/ui/associated-types/issue-85103.stderr b/src/test/ui/associated-types/issue-85103.stderr
new file mode 100644
index 000000000000..142f3c411ec5
--- /dev/null
+++ b/src/test/ui/associated-types/issue-85103.stderr
@@ -0,0 +1,8 @@
+error: layout error: NormalizationFailure(<[E] as std::borrow::ToOwned>::Owned, Type(<[E] as std::borrow::ToOwned>::Owned))
+  --> $DIR/issue-85103.rs:6:1
+   |
+LL | type Edges<'a, E> = Cow<'a, [E]>;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/associated-types/issue-91231.rs b/src/test/ui/associated-types/issue-91231.rs
new file mode 100644
index 000000000000..3c1cb81f0975
--- /dev/null
+++ b/src/test/ui/associated-types/issue-91231.rs
@@ -0,0 +1,17 @@
+// check-pass
+
+#![feature(extern_types)]
+#![allow(dead_code)]
+
+extern {
+    type Extern;
+}
+
+trait Trait {
+    type Type;
+}
+
+#[inline]
+fn f<'a>(_: <&'a Extern as Trait>::Type) where &'a Extern: Trait {}
+
+fn main() {}