diff --git a/stdlib/public/runtime/Casting.cpp b/stdlib/public/runtime/Casting.cpp
index c8349b170830d..c25154c8d061a 100644
--- a/stdlib/public/runtime/Casting.cpp
+++ b/stdlib/public/runtime/Casting.cpp
@@ -403,7 +403,7 @@ static bool _conformsToProtocols(const OpaqueValue *value,
   for (auto protocol : existentialType->getProtocols()) {
     if (!_conformsToProtocol(value, type, protocol, conformances))
       return false;
-    if (protocol.needsWitnessTable()) {
+    if (conformances != nullptr && protocol.needsWitnessTable()) {
       assert(*conformances != nullptr);
       ++conformances;
     }
@@ -1115,6 +1115,13 @@ swift_dynamicCastMetatypeImpl(const Metadata *sourceType,
     }
     break;
 
+  case MetadataKind::Existential: {
+    auto targetTypeAsExistential = static_cast<const ExistentialTypeMetadata *>(targetType);
+    if (!_conformsToProtocols(nullptr, sourceType, targetTypeAsExistential, nullptr))
+      return nullptr;
+    return origSourceType;
+  }
+
   default:
     // The cast succeeds only if the metadata pointers are statically
     // equivalent.
diff --git a/test/Interpreter/generic_casts.swift b/test/Interpreter/generic_casts.swift
index bf87feb633bfb..0f9c359bdda06 100644
--- a/test/Interpreter/generic_casts.swift
+++ b/test/Interpreter/generic_casts.swift
@@ -1,4 +1,6 @@
-// RUN: %target-run-simple-swift | %FileCheck %s
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift -Onone %s -o %t/a.out
+// RUN: %target-run %t/a.out | %FileCheck --check-prefix CHECK --check-prefix CHECK-ONONE %s
 // RUN: %target-build-swift -O %s -o %t/a.out.optimized
 // RUN: %target-codesign %t/a.out.optimized
 // RUN: %target-run %t/a.out.optimized | %FileCheck %s
@@ -131,6 +133,58 @@ anyClassToCOrE(C()).print() // CHECK: C!
 anyClassToCOrE(D()).print() // CHECK: D!
 anyClassToCOrE(X()).print() // CHECK: E!
 
+protocol P {}
+struct PS: P {}
+enum PE: P {}
+class PC: P {}
+class PCSub: PC {}
+
+func nongenericAnyIsP(type: Any.Type) -> Bool {
+  return type is P.Type
+}
+func nongenericAnyIsPAndAnyObject(type: Any.Type) -> Bool {
+  return type is (P & AnyObject).Type
+}
+func nongenericAnyIsPAndPCSub(type: Any.Type) -> Bool {
+  return type is (P & PCSub).Type
+}
+func genericAnyIs<T>(type: Any.Type, to: T.Type) -> Bool {
+  return type is T.Type
+}
+// CHECK-LABEL: casting types to protocols with generics:
+print("casting types to protocols with generics:")
+print(nongenericAnyIsP(type: PS.self)) // CHECK: true
+print(genericAnyIs(type: PS.self, to: P.self)) // CHECK-ONONE: true
+print(nongenericAnyIsP(type: PE.self)) // CHECK: true
+print(genericAnyIs(type: PE.self, to: P.self)) // CHECK-ONONE: true
+print(nongenericAnyIsP(type: PC.self)) // CHECK: true
+print(genericAnyIs(type: PC.self, to: P.self)) // CHECK-ONONE: true
+print(nongenericAnyIsP(type: PCSub.self)) // CHECK: true
+print(genericAnyIs(type: PCSub.self, to: P.self)) // CHECK-ONONE: true
+
+// CHECK-LABEL: casting types to protocol & AnyObject existentials:
+print("casting types to protocol & AnyObject existentials:")
+print(nongenericAnyIsPAndAnyObject(type: PS.self)) // CHECK: false
+print(genericAnyIs(type: PS.self, to: (P & AnyObject).self)) // CHECK: false
+print(nongenericAnyIsPAndAnyObject(type: PE.self)) // CHECK: false
+print(genericAnyIs(type: PE.self, to: (P & AnyObject).self)) // CHECK: false
+print(nongenericAnyIsPAndAnyObject(type: PC.self)) // CHECK: true
+print(genericAnyIs(type: PC.self, to: (P & AnyObject).self)) // CHECK-ONONE: true
+print(nongenericAnyIsPAndAnyObject(type: PCSub.self)) // CHECK: true
+print(genericAnyIs(type: PCSub.self, to: (P & AnyObject).self)) // CHECK-ONONE: true
+
+// CHECK-LABEL: casting types to protocol & class existentials:
+print("casting types to protocol & class existentials:")
+print(nongenericAnyIsPAndPCSub(type: PS.self)) // CHECK: false
+print(genericAnyIs(type: PS.self, to: (P & PCSub).self)) // CHECK: false
+print(nongenericAnyIsPAndPCSub(type: PE.self)) // CHECK: false
+print(genericAnyIs(type: PE.self, to: (P & PCSub).self)) // CHECK: false
+//print(nongenericAnyIsPAndPCSub(type: PC.self)) // CHECK-SR-11565: false -- FIXME: reenable this when SR-11565 is fixed
+print(genericAnyIs(type: PC.self, to: (P & PCSub).self)) // CHECK: false
+print(nongenericAnyIsPAndPCSub(type: PCSub.self)) // CHECK: true
+print(genericAnyIs(type: PCSub.self, to: (P & PCSub).self)) // CHECK-ONONE: true
+
+
 // CHECK-LABEL: type comparisons:
 print("type comparisons:\n")
 print(allMetasToAllMetas(Int.self, Int.self)) // CHECK: true
diff --git a/test/Interpreter/generic_casts_objc.swift b/test/Interpreter/generic_casts_objc.swift
new file mode 100644
index 0000000000000..a228d4f18402a
--- /dev/null
+++ b/test/Interpreter/generic_casts_objc.swift
@@ -0,0 +1,33 @@
+// RUN: %target-run-simple-swift | %FileCheck --check-prefix CHECK --check-prefix CHECK-ONONE --dump-input fail %s
+// RUN: %target-build-swift -O %s -o %t/a.out.optimized
+// RUN: %target-codesign %t/a.out.optimized
+// RUN: %target-run %t/a.out.optimized | %FileCheck %s
+// REQUIRES: executable_test
+// REQUIRES: objc_interop
+
+import Foundation
+
+protocol P {}
+@objc protocol PObjC {}
+struct PS: P {}
+enum PE: P {}
+class PC: P, PObjC {}
+class PCSub: PC {}
+
+func nongenericAnyIsPObjC(type: Any.Type) -> Bool {
+  return type is PObjC.Type
+}
+func genericAnyIs<T>(type: Any.Type, to: T.Type) -> Bool {
+  return type is T.Type
+}
+
+// CHECK-LABEL: casting types to ObjC protocols with generics:
+print("casting types to ObjC protocols with generics:")
+print(nongenericAnyIsPObjC(type: PS.self)) // CHECK: false
+print(genericAnyIs(type: PS.self, to: PObjC.self)) // CHECK: false
+print(nongenericAnyIsPObjC(type: PE.self)) // CHECK: false
+print(genericAnyIs(type: PE.self, to: PObjC.self)) // CHECK: false
+print(nongenericAnyIsPObjC(type: PC.self)) // CHECK: true
+print(genericAnyIs(type: PC.self, to: PObjC.self)) // CHECK-ONONE: true
+print(nongenericAnyIsPObjC(type: PCSub.self)) // CHECK: true
+print(genericAnyIs(type: PCSub.self, to: PObjC.self)) // CHECK-ONONE: true