diff --git a/include/swift/AST/Types.h b/include/swift/AST/Types.h
index 55154c3..b34b28d 100644
--- a/include/swift/AST/Types.h
+++ b/include/swift/AST/Types.h
@@ -4034,7 +4034,8 @@
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getGenericSignature(), getExtInfo(), getCoroutineKind(),
             getCalleeConvention(), getParameters(), getYields(),
-            getResults(), getOptionalErrorResult());
+            getResults(), getOptionalErrorResult(),
+            getWitnessMethodConformanceOrNone());
   }
   static void Profile(llvm::FoldingSetNodeID &ID,
                       GenericSignature *genericSig,
@@ -4044,7 +4045,8 @@
                       ArrayRef<SILParameterInfo> params,
                       ArrayRef<SILYieldInfo> yields,
                       ArrayRef<SILResultInfo> results,
-                      Optional<SILResultInfo> errorResult);
+                      Optional<SILResultInfo> errorResult,
+                      Optional<ProtocolConformanceRef> conformance);
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const TypeBase *T) {
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index f5542e1..309421f 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -3863,7 +3863,8 @@
                               ArrayRef<SILParameterInfo> params,
                               ArrayRef<SILYieldInfo> yields,
                               ArrayRef<SILResultInfo> results,
-                              Optional<SILResultInfo> errorResult) {
+                              Optional<SILResultInfo> errorResult,
+                              Optional<ProtocolConformanceRef> conformance) {
   id.AddPointer(genericParams);
   id.AddInteger(info.getFuncAttrKey());
   id.AddInteger(unsigned(coroutineKind));
@@ -3881,6 +3882,8 @@
   // Just allow the profile length to implicitly distinguish the
   // presence of an error result.
   if (errorResult) errorResult->profile(id);
+  if (conformance)
+    id.AddPointer(conformance->getRequirement());
 }
 
 SILFunctionType::SILFunctionType(GenericSignature *genericSig, ExtInfo ext,
@@ -4016,8 +4019,9 @@
   assert(coroutineKind != SILCoroutineKind::None || yields.empty());
 
   llvm::FoldingSetNodeID id;
-  SILFunctionType::Profile(id, genericSig, ext, coroutineKind, callee,
-                           params, yields, normalResults, errorResult);
+  SILFunctionType::Profile(id, genericSig, ext, coroutineKind, callee, params,
+                           yields, normalResults, errorResult,
+                           witnessMethodConformance);
 
   // Do we already have this generic function type?
   void *insertPos;
diff --git a/test/SILGen/witnesses.swift b/test/SILGen/witnesses.swift
index fe4f550..dab1df7 100644
--- a/test/SILGen/witnesses.swift
+++ b/test/SILGen/witnesses.swift
@@ -337,7 +337,7 @@
 struct NonFailableModel: FailableRequirement, NonFailableRefinement, IUOFailableRequirement {
   // CHECK-LABEL: sil private [transparent] [thunk] @$S9witnesses16NonFailableModelVAA0C11Requirement{{[_0-9a-zA-Z]*}}fCTW : $@convention(witness_method: FailableRequirement) (Int, @thick NonFailableModel.Type) -> @out Optional<NonFailableModel>
   // CHECK-LABEL: sil private [transparent] [thunk] @$S9witnesses16NonFailableModelVAA0bC10Refinement{{[_0-9a-zA-Z]*}}fCTW : $@convention(witness_method: NonFailableRefinement) (Int, @thick NonFailableModel.Type) -> @out NonFailableModel
-  // CHECK-LABEL: sil private [transparent] [thunk] @$S9witnesses16NonFailableModelVAA22IUOFailableRequirement{{[_0-9a-zA-Z]*}}fCTW : $@convention(witness_method: FailableRequirement) (Int, @thick NonFailableModel.Type) -> @out Optional<NonFailableModel>
+  // CHECK-LABEL: sil private [transparent] [thunk] @$S9witnesses16NonFailableModelVAA22IUOFailableRequirement{{[_0-9a-zA-Z]*}}fCTW : $@convention(witness_method: IUOFailableRequirement) (Int, @thick NonFailableModel.Type) -> @out Optional<NonFailableModel>
   init(foo: Int) {}
 }
 
@@ -380,7 +380,7 @@
 final class NonFailableClassModel: FailableClassRequirement, NonFailableClassRefinement, IUOFailableClassRequirement {
   // CHECK-LABEL: sil private [transparent] [thunk] @$S9witnesses21NonFailableClassModelCAA0cD11Requirement{{[_0-9a-zA-Z]*}}fCTW : $@convention(witness_method: FailableClassRequirement) (Int, @thick NonFailableClassModel.Type) -> @owned Optional<NonFailableClassModel>
   // CHECK-LABEL: sil private [transparent] [thunk] @$S9witnesses21NonFailableClassModelCAA0bcD10Refinement{{[_0-9a-zA-Z]*}}fCTW : $@convention(witness_method: NonFailableClassRefinement) (Int, @thick NonFailableClassModel.Type) -> @owned NonFailableClassModel
-  // CHECK-LABEL: sil private [transparent] [thunk] @$S9witnesses21NonFailableClassModelCAA011IUOFailableD11Requirement{{[_0-9a-zA-Z]*}}fCTW : $@convention(witness_method: FailableClassRequirement) (Int, @thick NonFailableClassModel.Type) -> @owned Optional<NonFailableClassModel>
+  // CHECK-LABEL: sil private [transparent] [thunk] @$S9witnesses21NonFailableClassModelCAA011IUOFailableD11Requirement{{[_0-9a-zA-Z]*}}fCTW : $@convention(witness_method: IUOFailableClassRequirement) (Int, @thick NonFailableClassModel.Type) -> @owned Optional<NonFailableClassModel>
   init(foo: Int) {}
 }
 
@@ -525,3 +525,22 @@
 struct EscapingCovariance: EscapingReq {
   func f(_: (Int) -> Int) { }
 }
+
+
+protocol Base {
+  func foo()
+}
+
+protocol Sub : Base {
+  func bar()
+}
+
+struct MyImpl :Sub {
+  func bar() {}
+	func foo() {}
+}
+
+// protocol witness for witnesses.Sub.bar() -> () in conformance witnesses.MyImpl : witnesses.Sub in witnesses
+// CHECK: sil private [transparent] [thunk] @$S9witnesses6MyImplVAA3SubA2aDP3baryyFTW : $@convention(witness_method: Sub) (@in_guaranteed MyImpl) -> ()
+// protocol witness for witnesses.Base.foo() -> () in conformance witnesses.MyImpl : witnesses.Base in witnesses
+// CHECK: sil private [transparent] [thunk] @$S9witnesses6MyImplVAA4BaseA2aDP3fooyyFTW : $@convention(witness_method: Base) (@in_guaranteed MyImpl) -> ()