diff --git a/include/swift/AST/DiagnosticsSema.def b/include/swift/AST/DiagnosticsSema.def
index c070e1e0c42de..cef4f821235f5 100644
--- a/include/swift/AST/DiagnosticsSema.def
+++ b/include/swift/AST/DiagnosticsSema.def
@@ -1798,9 +1798,16 @@ ERROR(mutating_invalid_classes,none, "%0 is not valid on %kindonly1s in "
 ERROR(functions_mutating_and_not,none,
       "method must not be declared both %0 and %1",
       (SelfAccessKind, SelfAccessKind))
+
 ERROR(static_functions_not_mutating,none,
       "static functions must not be declared mutating", ())
 
+ERROR(consuming_invalid_borrow_mutate_accessor, none,
+      "%0 cannot be declared consuming", (StringRef))
+
+ERROR(ownership_modifier_unsupported_borrow_mutate_accessor, none,
+      "%0 ownership modifier is not yet supported on %1", (StringRef, StringRef))
+
 ERROR(readwriter_mutatingness_differs_from_reader_or_writer_mutatingness,none,
       "%0 cannot be %1 when "
       "%select{both the %3 is %4 and the %5 is not %6|either the %3 is not %4 or the %5 is %6|the %3 is not %4|the %5 is %6}2",
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index a90887793eced..531f93de2bf2f 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -3264,6 +3264,10 @@ static AccessStrategy getOpaqueReadAccessStrategy(
     return AccessStrategy::getAccessor(AccessorKind::Read2, dispatch);
   if (storage->requiresOpaqueReadCoroutine())
     return AccessStrategy::getAccessor(AccessorKind::Read, dispatch);
+
+  if (storage->getParsedAccessor(AccessorKind::Borrow)) {
+    return AccessStrategy::getAccessor(AccessorKind::Borrow, dispatch);
+  }
   return AccessStrategy::getAccessor(AccessorKind::Get, dispatch);
 }
 
@@ -3435,11 +3439,6 @@ bool AbstractStorageDecl::requiresOpaqueSetter() const {
   if (!supportsMutation()) {
     return false;
   }
-
-  // If a mutate accessor is present, we don't need a setter.
-  if (getAccessor(AccessorKind::Mutate)) {
-    return false;
-  }
   return true;
 }
 
@@ -3450,7 +3449,7 @@ bool AbstractStorageDecl::requiresOpaqueReadCoroutine() const {
         AccessorKind::Read2);
 
   // If a borrow accessor is present, we don't need a read coroutine.
-  if (getAccessor(AccessorKind::Borrow)) {
+  if (getParsedAccessor(AccessorKind::Borrow)) {
     return false;
   }
   return getOpaqueReadOwnership() != OpaqueReadOwnership::Owned;
@@ -3462,7 +3461,7 @@ bool AbstractStorageDecl::requiresOpaqueRead2Coroutine() const {
     return false;
 
   // If a borrow accessor is present, we don't need a read coroutine.
-  if (getAccessor(AccessorKind::Borrow)) {
+  if (getParsedAccessor(AccessorKind::Borrow)) {
     return false;
   }
   return getOpaqueReadOwnership() != OpaqueReadOwnership::Owned;
@@ -7595,7 +7594,7 @@ StringRef swift::getAccessorNameForDiagnostic(AccessorKind accessorKind,
   case AccessorKind::Init:
     return article ? "an init accessor" : "init accessor";
   case AccessorKind::Borrow:
-    return article ? " a 'borrow' accessor" : "borrow accessor";
+    return article ? "a 'borrow' accessor" : "borrow accessor";
   case AccessorKind::Mutate:
     return article ? "a 'mutate' accessor" : "mutate accessor";
   }
diff --git a/lib/Sema/TypeCheckAttr.cpp b/lib/Sema/TypeCheckAttr.cpp
index d7f039864f12a..18c85bc97269a 100644
--- a/lib/Sema/TypeCheckAttr.cpp
+++ b/lib/Sema/TypeCheckAttr.cpp
@@ -708,6 +708,31 @@ void AttributeChecker::visitMutationAttr(DeclAttribute *attr) {
   // Verify that we don't have a static function.
   if (FD->isStatic())
     diagnoseAndRemoveAttr(attr, diag::static_functions_not_mutating);
+
+  auto *accessor = dyn_cast<AccessorDecl>(FD);
+  if (accessor &&
+      (accessor->isBorrowAccessor() || accessor->isMutateAccessor())) {
+    if (attrModifier == SelfAccessKind::Consuming ||
+        attrModifier == SelfAccessKind::LegacyConsuming) {
+      diagnoseAndRemoveAttr(
+          attr, diag::consuming_invalid_borrow_mutate_accessor,
+          getAccessorNameForDiagnostic(accessor, /*article*/ true));
+    }
+    if (attrModifier == SelfAccessKind::NonMutating &&
+        accessor->isMutateAccessor()) {
+      diagnoseAndRemoveAttr(
+          attr, diag::ownership_modifier_unsupported_borrow_mutate_accessor,
+          attr->getAttrName(),
+          getAccessorNameForDiagnostic(accessor, /*article*/ true));
+    }
+    if (attrModifier == SelfAccessKind::Mutating &&
+        accessor->isBorrowAccessor()) {
+      diagnoseAndRemoveAttr(
+          attr, diag::ownership_modifier_unsupported_borrow_mutate_accessor,
+          attr->getAttrName(),
+          getAccessorNameForDiagnostic(accessor, /*article*/ true));
+    }
+  }
 }
 
 void AttributeChecker::visitDynamicAttr(DynamicAttr *attr) {
diff --git a/lib/Sema/TypeCheckStorage.cpp b/lib/Sema/TypeCheckStorage.cpp
index b4533b79623e9..4bbb1e5f49477 100644
--- a/lib/Sema/TypeCheckStorage.cpp
+++ b/lib/Sema/TypeCheckStorage.cpp
@@ -1875,6 +1875,13 @@ synthesizeModify2CoroutineSetterBody(AccessorDecl *setter, ASTContext &ctx) {
       setter, TargetImpl::Implementation, setter->getStorage(), ctx);
 }
 
+static std::pair<BraceStmt *, bool>
+synthesizeMutateSetterBody(AccessorDecl *setter, ASTContext &ctx) {
+  // This should call the mutate accessor.
+  return synthesizeTrivialSetterBodyWithStorage(
+      setter, TargetImpl::Implementation, setter->getStorage(), ctx);
+}
+
 static Expr *maybeWrapInOutExpr(Expr *expr, ASTContext &ctx) {
   if (auto lvalueType = expr->getType()->getAs<LValueType>()) {
     auto type = lvalueType->getObjectType();
@@ -2071,7 +2078,7 @@ synthesizeSetterBody(AccessorDecl *setter, ASTContext &ctx) {
     return synthesizeModify2CoroutineSetterBody(setter, ctx);
 
   case WriteImplKind::Mutate:
-    llvm_unreachable("synthesizing setter from mutate");
+    return synthesizeMutateSetterBody(setter, ctx);
   }
   llvm_unreachable("bad WriteImplKind");
 }
@@ -2476,7 +2483,9 @@ static AccessorDecl *createSetterPrototype(AbstractStorageDecl *storage,
     }
     break;
   case WriteImplKind::Mutate:
-    llvm_unreachable("mutate accessor is not yet implemented");
+    if (auto mutate = storage->getOpaqueAccessor(AccessorKind::Mutate)) {
+      asAvailableAs.push_back(mutate);
+    }
   }
   
   if (!asAvailableAs.empty()) {
@@ -2804,11 +2813,6 @@ bool RequiresOpaqueModifyCoroutineRequest::evaluate(
     if (protoDecl->isObjC())
       return false;
 
-  // If a mutate accessor is present, we don't need a modify coroutine
-  if (storage->getAccessor(AccessorKind::Mutate)) {
-    return false;
-  }
-
   return true;
 }
 
@@ -2937,9 +2941,8 @@ IsAccessorTransparentRequest::evaluate(Evaluator &evaluator,
     case WriteImplKind::MutableAddress:
     case WriteImplKind::Modify:
     case WriteImplKind::Modify2:
-      break;
     case WriteImplKind::Mutate:
-      llvm_unreachable("mutate accessor is not yet implemented");
+      break;
     }
     break;
 
@@ -2950,14 +2953,12 @@ IsAccessorTransparentRequest::evaluate(Evaluator &evaluator,
   case AccessorKind::Init:
     break;
   case AccessorKind::Borrow:
-    llvm_unreachable("borrow accessor is not yet implemented");
   case AccessorKind::WillSet:
   case AccessorKind::DidSet:
   case AccessorKind::Address:
   case AccessorKind::MutableAddress:
-    llvm_unreachable("bad synthesized function kind");
   case AccessorKind::Mutate:
-    llvm_unreachable("mutate accessor is not yet implemented");
+    llvm_unreachable("bad synthesized function kind");
   }
 
   switch (storage->getReadWriteImpl()) {
diff --git a/test/IRGen/borrow_accessor_large.swift b/test/IRGen/borrow_accessor_large.swift
index 753e6a95e3f9c..8b8dfec0980ca 100644
--- a/test/IRGen/borrow_accessor_large.swift
+++ b/test/IRGen/borrow_accessor_large.swift
@@ -1,4 +1,5 @@
 // RUN: %target-swift-frontend -c %s -Xllvm -sil-print-after=loadable-address  -enable-experimental-feature BorrowAndMutateAccessors  2>&1 | %FileCheck %s
+// RUN: %target-swift-frontend -emit-irgen %s -enable-experimental-feature BorrowAndMutateAccessors  2>&1 | %FileCheck --check-prefixes=CHECK-IRGEN  %s
 
 // REQUIRES: swift_feature_BorrowAndMutateAccessors
 // REQUIRES: OS=macosx
@@ -137,9 +138,9 @@ func nctest() {
 // CHECK: }
 
 // IRGen result type is PtrTy because we are returning a class reference 
-// CHECK-IRGEN: define hidden swiftcc ptr @"$s21borrow_accessor_large11LargeStructV0A5KlassAA0F0Cvb"(ptr noalias nocapture swiftself dereferenceable(208) [[REG0]]) {{.*}} {
+// CHECK-IRGEN: define hidden swiftcc ptr @"$s21borrow_accessor_large11LargeStructV0A5KlassAA0F0Cvb"(ptr noalias swiftself captures(none) dereferenceable(208) [[REG0:%.*]]) {{.*}} {
 // CHECK-IRGEN: entry:
-// CHECK-IRGEN:   %._k = getelementptr inbounds %T21borrow_accessor_large11LargeStructV, ptr [[REG0]], i32 0, i32 0
+// CHECK-IRGEN:   %._k = getelementptr inbounds nuw %T21borrow_accessor_large11LargeStructV, ptr [[REG0]], i32 0, i32 0
 // CHECK-IRGEN:   [[REG1:%.*]] = load ptr, ptr %._k, align 8
 // CHECK-IRGEN:   ret ptr [[REG1]]
 // CHECK-IRGEN: }
@@ -151,11 +152,11 @@ func nctest() {
 // CHECK:   return [[REG3]]
 // CHECK: }
 
-// CHECK-IRGEN: define hidden swiftcc i64 @"$s21borrow_accessor_large11LargeStructV0a5SmallE0AA0fE0Vvb"(ptr noalias nocapture swiftself dereferenceable(208) [[REG0]]) {{.*}} {
+// CHECK-IRGEN: define hidden swiftcc i64 @"$s21borrow_accessor_large11LargeStructV0a5SmallE0AA0fE0Vvb"(ptr noalias swiftself captures(none) dereferenceable(208) [[REG0:%.*]]) {{.*}} {
 // CHECK-IRGEN: entry:
-// CHECK-IRGEN:   %._smallStruct = getelementptr inbounds %T21borrow_accessor_large11LargeStructV, ptr [[REG0]], i32 0, i32 4
-// CHECK-IRGEN:   %._smallStruct.id = getelementptr inbounds %T21borrow_accessor_large11SmallStructV, ptr %._smallStruct, i32 0, i32 0
-// CHECK-IRGEN:   %._smallStruct.id._value = getelementptr inbounds %TSi, ptr %._smallStruct.id, i32 0, i32 0
+// CHECK-IRGEN:   %._smallStruct = getelementptr inbounds nuw %T21borrow_accessor_large11LargeStructV, ptr [[REG0]], i32 0, i32 4
+// CHECK-IRGEN:   %._smallStruct.id = getelementptr inbounds nuw %T21borrow_accessor_large11SmallStructV, ptr %._smallStruct, i32 0, i32 0
+// CHECK-IRGEN:   %._smallStruct.id._value = getelementptr inbounds nuw %TSi, ptr %._smallStruct.id, i32 0, i32 0
 // CHECK-IRGEN:   [[REG1:%.*]] = load i64, ptr %._smallStruct.id._value, align 8
 // CHECK-IRGEN:   ret i64 [[REG1]]
 // CHECK-IRGEN: }
@@ -169,9 +170,9 @@ func nctest() {
 // CHECK:   return [[REG5]]
 // CHECK: }
 
-// CHECK-IRGEN: define hidden swiftcc void @"$s21borrow_accessor_large11LargeStructV0C10PropBorrowAA0dF0Vvb"(ptr noalias nocapture sret(%T21borrow_accessor_large9LargePropV) [[REG0]], ptr noalias nocapture swiftself dereferenceable(208) [[REG1]]) {{.*}} {
+// CHECK-IRGEN: define hidden swiftcc void @"$s21borrow_accessor_large11LargeStructV0C10PropBorrowAA0dF0Vvb"(ptr noalias sret(%T21borrow_accessor_large9LargePropV) captures(none) [[REG0:%.*]], ptr noalias swiftself captures(none) dereferenceable(208) [[REG1:%.*]]) {{.*}} {
 // CHECK-IRGEN: entry:
-// CHECK-IRGEN:   %._largeProp = getelementptr inbounds %T21borrow_accessor_large11LargeStructV, ptr [[REG1]], i32 0, i32 3
+// CHECK-IRGEN:   %._largeProp = getelementptr inbounds nuw %T21borrow_accessor_large11LargeStructV, ptr [[REG1]], i32 0, i32 3
 // CHECK-IRGEN:   call void @llvm.memcpy.p0.p0.i64(ptr align 8 [[REG0]], ptr align 8 %._largeProp, i64 64, i1 false)
 // CHECK-IRGEN:   ret void
 // CHECK-IRGEN: }
@@ -184,40 +185,40 @@ func nctest() {
 // CHECK:   return [[REG3]]
 // CHECK: }
 
-// CHECK-IRGEN: define hidden swiftcc void @"$s21borrow_accessor_large11LargeStructV0C11TupleBorrowAA5KlassC_A7Ftvb"(ptr noalias nocapture sret(<{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>) [[REG0]], ptr noalias nocapture swiftself dereferenceable(208) [[REG1]]) {{.*}} {
+// CHECK-IRGEN: define hidden swiftcc void @"$s21borrow_accessor_large11LargeStructV0C11TupleBorrowAA5KlassC_A7Ftvb"(ptr noalias sret(<{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>) captures(none) [[REG0:%.*]], ptr noalias swiftself captures(none) dereferenceable(208) [[REG1:%.*]]) {{.*}} {
 // CHECK-IRGEN: entry:
-// CHECK-IRGEN:   %._largeTuple = getelementptr inbounds %T21borrow_accessor_large11LargeStructV, ptr [[REG1]], i32 0, i32 2
-// CHECK-IRGEN:   %._largeTuple.elt = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 0
+// CHECK-IRGEN:   %._largeTuple = getelementptr inbounds nuw %T21borrow_accessor_large11LargeStructV, ptr [[REG1]], i32 0, i32 2
+// CHECK-IRGEN:   %._largeTuple.elt = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 0
 // CHECK-IRGEN:   [[REG2:%.*]] = load ptr, ptr %._largeTuple.elt, align 8
-// CHECK-IRGEN:   %._largeTuple.elt1 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 1
+// CHECK-IRGEN:   %._largeTuple.elt1 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 1
 // CHECK-IRGEN:   [[REG3:%.*]] = load ptr, ptr %._largeTuple.elt1, align 8
-// CHECK-IRGEN:   %._largeTuple.elt2 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 2
+// CHECK-IRGEN:   %._largeTuple.elt2 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 2
 // CHECK-IRGEN:   [[REG4:%.*]] = load ptr, ptr %._largeTuple.elt2, align 8
-// CHECK-IRGEN:   %._largeTuple.elt3 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 3
+// CHECK-IRGEN:   %._largeTuple.elt3 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 3
 // CHECK-IRGEN:   [[REG5:%.*]] = load ptr, ptr %._largeTuple.elt3, align 8
-// CHECK-IRGEN:   %._largeTuple.elt4 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 4
+// CHECK-IRGEN:   %._largeTuple.elt4 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 4
 // CHECK-IRGEN:   [[REG6:%.*]] = load ptr, ptr %._largeTuple.elt4, align 8
-// CHECK-IRGEN:   %._largeTuple.elt5 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 5
+// CHECK-IRGEN:   %._largeTuple.elt5 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 5
 // CHECK-IRGEN:   [[REG7:%.*]] = load ptr, ptr %._largeTuple.elt5, align 8
-// CHECK-IRGEN:   %._largeTuple.elt6 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 6
+// CHECK-IRGEN:   %._largeTuple.elt6 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 6
 // CHECK-IRGEN:   [[REG8:%.*]] = load ptr, ptr %._largeTuple.elt6, align 8
-// CHECK-IRGEN:   %._largeTuple.elt7 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 7
+// CHECK-IRGEN:   %._largeTuple.elt7 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr %._largeTuple, i32 0, i32 7
 // CHECK-IRGEN:   [[REG9:%.*]] = load ptr, ptr %._largeTuple.elt7, align 8
-// CHECK-IRGEN:   %.elt = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 0
+// CHECK-IRGEN:   %.elt = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 0
 // CHECK-IRGEN:   store ptr [[REG2]], ptr %.elt, align 8
-// CHECK-IRGEN:   %.elt8 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 1
+// CHECK-IRGEN:   %.elt8 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 1
 // CHECK-IRGEN:   store ptr [[REG3]], ptr %.elt8, align 8
-// CHECK-IRGEN:   %.elt9 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 2
+// CHECK-IRGEN:   %.elt9 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 2
 // CHECK-IRGEN:   store ptr [[REG4]], ptr %.elt9, align 8
-// CHECK-IRGEN:   %.elt10 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 3
+// CHECK-IRGEN:   %.elt10 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 3
 // CHECK-IRGEN:   store ptr [[REG5]], ptr %.elt10, align 8
-// CHECK-IRGEN:   %.elt11 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 4
+// CHECK-IRGEN:   %.elt11 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 4
 // CHECK-IRGEN:   store ptr [[REG6]], ptr %.elt11, align 8
-// CHECK-IRGEN:   %.elt12 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 5
+// CHECK-IRGEN:   %.elt12 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 5
 // CHECK-IRGEN:   store ptr [[REG7]], ptr %.elt12, align 8
-// CHECK-IRGEN:   %.elt13 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 6
+// CHECK-IRGEN:   %.elt13 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 6
 // CHECK-IRGEN:   store ptr [[REG8]], ptr %.elt13, align 8
-// CHECK-IRGEN:   %.elt14 = getelementptr inbounds <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 7
+// CHECK-IRGEN:   %.elt14 = getelementptr inbounds nuw <{ ptr, ptr, ptr, ptr, ptr, ptr, ptr, ptr }>, ptr [[REG0]], i32 0, i32 7
 // CHECK-IRGEN:   store ptr [[REG9]], ptr %.elt14, align 8
 // CHECK-IRGEN:   ret void
 // CHECK-IRGEN: }
@@ -229,11 +230,11 @@ func nctest() {
 // CHECK:   return [[REG3]]
 // CHECK: }
 
-// CHECK-IRGEN: define hidden swiftcc i64 @"$s21borrow_accessor_large13NCLargeStructV0A2NCAA0F0Vvb"(ptr noalias nocapture swiftself dereferenceable(72) [[REG0]]) {{.*}} {
+// CHECK-IRGEN: define hidden swiftcc i64 @"$s21borrow_accessor_large13NCLargeStructV0A2NCAA0F0Vvb"(ptr noalias swiftself captures(none) dereferenceable(72) [[REG0:%.*]]) {{.*}} {
 // CHECK-IRGEN: entry:
-// CHECK-IRGEN:   %._k = getelementptr inbounds %T21borrow_accessor_large13NCLargeStructV, ptr [[REG0]], i32 0, i32 0
-// CHECK-IRGEN:   %._k.id = getelementptr inbounds %T21borrow_accessor_large2NCV, ptr %._k, i32 0, i32 0
-// CHECK-IRGEN:   %._k.id._value = getelementptr inbounds %TSi, ptr %._k.id, i32 0, i32 0
+// CHECK-IRGEN:   %._k = getelementptr inbounds nuw %T21borrow_accessor_large13NCLargeStructV, ptr [[REG0]], i32 0, i32 0
+// CHECK-IRGEN:   %._k.id = getelementptr inbounds nuw %T21borrow_accessor_large2NCV, ptr %._k, i32 0, i32 0
+// CHECK-IRGEN:   %._k.id._value = getelementptr inbounds nuw %TSi, ptr %._k.id, i32 0, i32 0
 // CHECK-IRGEN:   [[REG1:%.*]] = load i64, ptr %._k.id._value, align 8
 // CHECK-IRGEN:   ret i64 [[REG1]]
 // CHECK-IRGEN: }
@@ -247,9 +248,9 @@ func nctest() {
 // CHECK:   return [[REG5]]
 // CHECK: }
 
-// CHECK-IRGEN: define hidden swiftcc void @"$s21borrow_accessor_large13NCLargeStructV0C10PropBorrowAA11LargeNCPropVvb"(ptr noalias nocapture sret(%T21borrow_accessor_large11LargeNCPropV) [[REG0]], ptr noalias nocapture swiftself dereferenceable(72) [[REG1]]) {{.*}} {
+// CHECK-IRGEN: define hidden swiftcc void @"$s21borrow_accessor_large13NCLargeStructV0C10PropBorrowAA11LargeNCPropVvb"(ptr noalias sret(%T21borrow_accessor_large11LargeNCPropV) captures(none) [[REG0]], ptr noalias swiftself captures(none) dereferenceable(72) [[REG1:%.*]]) {{.*}} {
 // CHECK-IRGEN: entry:
-// CHECK-IRGEN:   %._largeProp = getelementptr inbounds %T21borrow_accessor_large13NCLargeStructV, ptr [[REG1]], i32 0, i32 1
+// CHECK-IRGEN:   %._largeProp = getelementptr inbounds nuw %T21borrow_accessor_large13NCLargeStructV, ptr [[REG1]], i32 0, i32 1
 // CHECK-IRGEN:   call void @llvm.memcpy.p0.p0.i64(ptr align 8 [[REG0]], ptr align 8 %._largeProp, i64 64, i1 false)
 // CHECK-IRGEN:   ret void
 // CHECK-IRGEN: }
diff --git a/test/Parse/borrow_and_mutate_accessors.swift b/test/Parse/borrow_and_mutate_accessors.swift
index f45e71fadd6d8..a723fb7f979bc 100644
--- a/test/Parse/borrow_and_mutate_accessors.swift
+++ b/test/Parse/borrow_and_mutate_accessors.swift
@@ -15,7 +15,7 @@ struct Wrapper {
     }
   }
   var k2: Klass {
-    borrow { // expected-error{{variable cannot provide both  a 'borrow' accessor and a getter}}
+    borrow { // expected-error{{variable cannot provide both a 'borrow' accessor and a getter}}
       return _k
     }
     get { // expected-note{{getter defined here}}
@@ -23,7 +23,7 @@ struct Wrapper {
     }
   }
   var k3: Klass {
-    borrow { // expected-error{{variable cannot provide both  a 'borrow' accessor and a '_read' accessor}}
+    borrow { // expected-error{{variable cannot provide both a 'borrow' accessor and a '_read' accessor}}
       return _k
     }
     _read { // expected-note{{'_read' accessor defined here}}
@@ -31,7 +31,7 @@ struct Wrapper {
     }
   }
   var k4: Klass {
-    borrow { // expected-error{{variable cannot provide both  a 'borrow' accessor and a 'read' accessor}}
+    borrow { // expected-error{{variable cannot provide both a 'borrow' accessor and a 'read' accessor}}
       return _k
     }
     read { // expected-note{{'read' accessor defined here}}
diff --git a/test/SILGen/borrow_accessor_synthesis.swift b/test/SILGen/borrow_accessor_synthesis.swift
new file mode 100644
index 0000000000000..77873de6ea7f3
--- /dev/null
+++ b/test/SILGen/borrow_accessor_synthesis.swift
@@ -0,0 +1,478 @@
+// RUN:%target-swift-frontend -emit-silgen %s -enable-experimental-feature BorrowAndMutateAccessors -enable-experimental-feature SuppressedAssociatedTypes -enable-library-evolution | %FileCheck %s
+
+// REQUIRES: swift_feature_BorrowAndMutateAccessors
+// REQUIRES: swift_feature_SuppressedAssociatedTypes
+
+public protocol P {
+  associatedtype Element
+  var prop1: Element { get set }
+  var prop2: Element { get set }
+  var prop3: Element { get set }
+}
+
+public class Klass {}
+
+public struct W<Element>: P {
+  var _prop: Element
+  public var prop1: Element {
+    borrow {
+      return _prop
+    }
+    mutate {
+      return &_prop
+    }
+  }
+
+  public var prop2: Element {
+    _read {
+      yield _prop
+    }
+    _modify {
+      yield &_prop
+    }
+  }
+
+  public var prop3: Element {
+    get {
+      return _prop
+    }
+    set {
+      _prop = newValue
+    }
+  }
+}
+
+public protocol NCP: ~Copyable {
+  associatedtype Element: ~Copyable
+  var prop1: Element { get set }
+  var prop2: Element { get set }
+  var prop3: Element { get set }
+}
+
+public struct NC<Element: ~Copyable>: NCP & ~Copyable {
+  var _prop: Element
+
+  public var prop1: Element {
+    borrow {
+      return _prop
+    }
+    mutate {
+      return &_prop
+    }
+  }
+
+  public var prop2: Element {
+    _read {
+      yield _prop
+    }
+    _modify {
+      yield &_prop
+    }
+  }
+
+  public var prop3: Element
+}
+
+func use<T: ~Copyable>(_ t: borrowing T) {}
+
+func mutate<T: ~Copyable>(_ t: inout T) {}
+
+// CHECK-LABEL: sil hidden [ossa] @$s25borrow_accessor_synthesis6testP1yyxAA1PRzlF : $@convention(thin) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*τ_0_0):
+// CHECK:   [[REG2:%.*]] = alloc_stack $(τ_0_0).Element
+// CHECK:   [[REG3:%.*]] = witness_method $τ_0_0, #P.prop1!getter : <Self where Self : P> (Self) -> () -> Self.Element : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG4:%.*]] = apply [[REG3]]<τ_0_0>([[REG2]], [[REG0]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG5:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG6:%.*]] = apply [[REG5]]<(τ_0_0).Element>([[REG2]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG2]]
+// CHECK:   dealloc_stack [[REG2]]
+// CHECK:   [[REG9:%.*]] = alloc_stack $(τ_0_0).Element
+// CHECK:   [[REG10:%.*]] = witness_method $τ_0_0, #P.prop2!getter : <Self where Self : P> (Self) -> () -> Self.Element : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG11:%.*]] = apply [[REG10]]<τ_0_0>([[REG9]], [[REG0]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG12:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG13:%.*]] = apply [[REG12]]<(τ_0_0).Element>([[REG9]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG9]]
+// CHECK:   dealloc_stack [[REG9]]
+// CHECK:   [[REG16:%.*]] = alloc_stack $(τ_0_0).Element
+// CHECK:   [[REG17:%.*]] = witness_method $τ_0_0, #P.prop3!getter : <Self where Self : P> (Self) -> () -> Self.Element : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG18:%.*]] = apply [[REG17]]<τ_0_0>([[REG16]], [[REG0]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG19:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG20:%.*]] = apply [[REG19]]<(τ_0_0).Element>([[REG16]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG16]]
+// CHECK:   dealloc_stack [[REG16]]
+// CHECK-LABEL: } // end sil function '$s25borrow_accessor_synthesis6testP1yyxAA1PRzlF'
+func testP1(_ p: some P) {
+  // For Copyable types, all opaque read accesses go through getter
+  // Conforming types can synthesize the getter from stored property, get, _read or borrow
+  use(p.prop1)
+  use(p.prop2)
+  use(p.prop3)
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis6testP2yyxzAA1PRzlF : $@convention(thin) <τ_0_0 where τ_0_0 : P> (@inout τ_0_0) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*τ_0_0):
+// CHECK:   [[REG2:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG3:%.*]] = witness_method $τ_0_0, #P.prop1!modify : <Self where Self : P> (inout Self) -> () -> () : $@yield_once @convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   ([[REG4]], [[REG5]]) = begin_apply [[REG3]]<τ_0_0>([[REG2]]) : $@yield_once @convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   [[REG6:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG7:%.*]] = apply [[REG6]]<(τ_0_0).Element>([[REG4]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG8:%.*]] = end_apply [[REG5]] as $()
+// CHECK:   end_access [[REG2]]
+// CHECK:   [[REG10:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG11:%.*]] = witness_method $τ_0_0, #P.prop2!modify : <Self where Self : P> (inout Self) -> () -> () : $@yield_once @convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   ([[REG12:%.*]], [[REG13:%.*]]) = begin_apply [[REG11]]<τ_0_0>([[REG10]]) : $@yield_once @convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   [[REG14:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG15:%.*]] = apply [[REG14]]<(τ_0_0).Element>([[REG12]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG16:%.*]] = end_apply [[REG13]] as $()
+// CHECK:   end_access [[REG10]]
+// CHECK:   [[REG18:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG19:%.*]] = witness_method $τ_0_0, #P.prop3!modify : <Self where Self : P> (inout Self) -> () -> () : $@yield_once @convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   ([[REG20:%.*]], [[REG21:%.*]]) = begin_apply [[REG19]]<τ_0_0>([[REG18]]) : $@yield_once @convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   [[REG22:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG23:%.*]] = apply [[REG22]]<(τ_0_0).Element>([[REG20]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG24:%.*]] = end_apply [[REG21]] as $()
+// CHECK:   end_access [[REG18]]
+// CHECK:   [[REG26:%.*]] = tuple ()
+// CHECK:   return [[REG26]]
+// CHECK: }
+func testP2(_ p: inout some P) {
+  // For Copyable types, all opaque modify accesses go through modify
+  // Conforming types can synthesize the modify from stored property, _modify or mutate
+  mutate(&p.prop1)
+  mutate(&p.prop2)
+  mutate(&p.prop3)
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis6testP3yyxzAA1PRzlF : $@convention(thin) <τ_0_0 where τ_0_0 : P> (@inout τ_0_0) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*τ_0_0):
+// CHECK:   [[REG2:%.*]] = begin_access [read] [unknown] [[REG0]]
+// CHECK:   [[REG3:%.*]] = alloc_stack $(τ_0_0).Element
+// CHECK:   [[REG4:%.*]] = witness_method $τ_0_0, #P.prop1!getter : <Self where Self : P> (Self) -> () -> Self.Element : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG5:%.*]] = apply [[REG4]]<τ_0_0>([[REG3]], [[REG2]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   end_access [[REG2]]
+// CHECK:   [[REG7:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG8:%.*]] = witness_method $τ_0_0, #P.prop1!setter : <Self where Self : P> (inout Self) -> (Self.Element) -> () : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in τ_0_0.Element, @inout τ_0_0) -> ()
+// CHECK:   [[REG9:%.*]] = apply [[REG8]]<τ_0_0>([[REG3]], [[REG7]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in τ_0_0.Element, @inout τ_0_0) -> ()
+// CHECK:   end_access [[REG7]]
+// CHECK:   dealloc_stack [[REG3]]
+// CHECK:   [[REG12:%.*]] = begin_access [read] [unknown] [[REG0]]
+// CHECK:   [[REG13:%.*]] = alloc_stack $(τ_0_0).Element
+// CHECK:   [[REG14:%.*]] = witness_method $τ_0_0, #P.prop2!getter : <Self where Self : P> (Self) -> () -> Self.Element : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG15:%.*]] = apply [[REG14]]<τ_0_0>([[REG13]], [[REG12]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   end_access [[REG12]]
+// CHECK:   [[REG17:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG18:%.*]] = witness_method $τ_0_0, #P.prop2!setter : <Self where Self : P> (inout Self) -> (Self.Element) -> () : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in τ_0_0.Element, @inout τ_0_0) -> ()
+// CHECK:   [[REG19:%.*]] = apply [[REG18]]<τ_0_0>([[REG13]], [[REG17]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in τ_0_0.Element, @inout τ_0_0) -> ()
+// CHECK:   end_access [[REG17]]
+// CHECK:   dealloc_stack [[REG13]]
+// CHECK:   [[REG22:%.*]] = begin_access [read] [unknown] [[REG0]]
+// CHECK:   [[REG23:%.*]] = alloc_stack $(τ_0_0).Element
+// CHECK:   [[REG24:%.*]] = witness_method $τ_0_0, #P.prop3!getter : <Self where Self : P> (Self) -> () -> Self.Element : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   [[REG25:%.*]] = apply [[REG24]]<τ_0_0>([[REG23]], [[REG22]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in_guaranteed τ_0_0) -> @out τ_0_0.Element
+// CHECK:   end_access [[REG22]]
+// CHECK:   [[REG27:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG28:%.*]] = witness_method $τ_0_0, #P.prop3!setter : <Self where Self : P> (inout Self) -> (Self.Element) -> () : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in τ_0_0.Element, @inout τ_0_0) -> ()
+// CHECK:   [[REG29:%.*]] = apply [[REG28]]<τ_0_0>([[REG23]], [[REG27]]) : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : P> (@in τ_0_0.Element, @inout τ_0_0) -> ()
+// CHECK:   end_access [[REG27]]
+// CHECK:   dealloc_stack [[REG23]]
+// CHECK:   [[REG32:%.*]] = tuple ()
+// CHECK:   return [[REG32]]
+// CHECK: }
+func testP3(_ p: inout some P) {
+  // For Copyable types, all opaque set accesses go through set
+  // Conforming types can synthesize the set from stored property, setter, _modify or mutate
+  p.prop1 = p.prop1
+  p.prop2 = p.prop2
+  p.prop3 = p.prop3
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis8testNCP1yyxAA3NCPRzlF : $@convention(thin) <τ_0_0 where τ_0_0 : NCP> (@in_guaranteed τ_0_0) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*τ_0_0):
+// CHECK:   [[REG2:%.*]] = witness_method $τ_0_0, #NCP.prop1!read : <Self where Self : NCP, Self : ~Copyable> (Self) -> () -> () : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> @yields @in_guaranteed τ_0_0.Element
+// CHECK:   ([[REG3:%.*]], [[REG4:%.*]]) = begin_apply [[REG2]]<τ_0_0>([[REG0]]) : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> @yields @in_guaranteed τ_0_0.Element
+// CHECK:   [[REG5:%.*]] = mark_unresolved_non_copyable_value [no_consume_or_assign] [[REG3]]
+// CHECK:   [[REG6:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG7:%.*]] = apply [[REG6]]<(τ_0_0).Element>([[REG5]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG8:%.*]] = end_apply [[REG4]] as $()
+// CHECK:   [[REG9:%.*]] = witness_method $τ_0_0, #NCP.prop2!read : <Self where Self : NCP, Self : ~Copyable> (Self) -> () -> () : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> @yields @in_guaranteed τ_0_0.Element
+// CHECK:   ([[REG10:%.*]], [[REG11:%.*]]) = begin_apply [[REG9]]<τ_0_0>([[REG0]]) : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> @yields @in_guaranteed τ_0_0.Element
+// CHECK:   [[REG12:%.*]] = mark_unresolved_non_copyable_value [no_consume_or_assign] [[REG10]]
+// CHECK:   [[REG13:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG14:%.*]] = apply [[REG13]]<(τ_0_0).Element>([[REG12]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG15:%.*]] = end_apply [[REG11]] as $()
+// CHECK:   [[REG16:%.*]] = witness_method $τ_0_0, #NCP.prop3!read : <Self where Self : NCP, Self : ~Copyable> (Self) -> () -> () : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> @yields @in_guaranteed τ_0_0.Element
+// CHECK:   [[REG19:%.*]] = mark_unresolved_non_copyable_value [no_consume_or_assign] [[REG17]]
+// CHECK:   [[REG20:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG21:%.*]] = apply [[REG20]]<(τ_0_0).Element>([[REG19]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG22:%.*]] = end_apply [[REG18]] as $()
+// CHECK: }
+func testNCP1(_ p: some NCP) {
+  use(p.prop1)
+  use(p.prop2)
+  use(p.prop3)
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis8testNCP2yyxzAA3NCPRzlF : $@convention(thin) <τ_0_0 where τ_0_0 : NCP> (@inout τ_0_0) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*τ_0_0):
+// CHECK:   [[REG2:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG3:%.*]] = witness_method $τ_0_0, #NCP.prop1!modify : <Self where Self : NCP, Self : ~Copyable> (inout Self) -> () -> () : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   ([[REG4:%.*]], [[REG5:%.*]]) = begin_apply [[REG3]]<τ_0_0>([[REG2]]) : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   [[REG6:%.*]] = mark_unresolved_non_copyable_value [consumable_and_assignable] [[REG4]]
+// CHECK:   [[REG7:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG8:%.*]] = apply [[REG7]]<(τ_0_0).Element>([[REG6]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG9:%.*]] = end_apply [[REG5]] as $()
+// CHECK:   end_access [[REG2]]
+// CHECK:   [[REG11:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG12:%.*]] = witness_method $τ_0_0, #NCP.prop2!modify : <Self where Self : NCP, Self : ~Copyable> (inout Self) -> () -> () : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   ([[REG13:%.*]], [[REG14:%.*]]) = begin_apply [[REG12]]<τ_0_0>([[REG11]]) : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   [[REG15:%.*]] = mark_unresolved_non_copyable_value [consumable_and_assignable] [[REG13]]
+// CHECK:   [[REG16:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG17:%.*]] = apply [[REG16]]<(τ_0_0).Element>([[REG15]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG18:%.*]] = end_apply [[REG14]] as $()
+// CHECK:   end_access [[REG11]]
+// CHECK:   [[REG20:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG21:%.*]] = witness_method $τ_0_0, #NCP.prop3!modify : <Self where Self : NCP, Self : ~Copyable> (inout Self) -> () -> () : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   ([[REG22:%.*]], [[REG23:%.*]]) = begin_apply [[REG21]]<τ_0_0>([[REG20]]) : $@yield_once @convention(witness_method: NCP) <τ_0_0 where τ_0_0 : NCP, τ_0_0 : ~Copyable> (@inout τ_0_0) -> @yields @inout τ_0_0.Element
+// CHECK:   [[REG24:%.*]] = mark_unresolved_non_copyable_value [consumable_and_assignable] [[REG22]]
+// CHECK:   [[REG25:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG26:%.*]] = apply [[REG25]]<(τ_0_0).Element>([[REG24]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG27:%.*]] = end_apply [[REG23]] as $()
+// CHECK:   end_access [[REG20]]
+// CHECK:   [[REG29:%.*]] = tuple ()
+// CHECK:   return [[REG29]]
+// CHECK: }
+func testNCP2(_ p: inout some NCP) {
+  mutate(&p.prop1)
+  mutate(&p.prop2)
+  mutate(&p.prop3)
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis6testW1yyAA1WVyxGlF : $@convention(thin) <T> (@in_guaranteed W<T>) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*W<T>):
+// CHECK:   [[REG2:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop1xvb : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @guaranteed_address τ_0_0
+// CHECK:   [[REG3:%.*]] = apply [[REG2]]<T>([[REG0]]) : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @guaranteed_address τ_0_0
+// CHECK:   [[REG4:%.*]] = alloc_stack $T
+// CHECK:   copy_addr [[REG3]] to [init] [[REG4]]
+// CHECK:   [[REG6:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG7:%.*]] = apply [[REG6]]<T>([[REG4]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG4]]
+// CHECK:   dealloc_stack [[REG4]]
+// CHECK:   [[REG10:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop2xvr : $@yield_once @convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @yields @in_guaranteed τ_0_0
+// CHECK:   ([[REG11:%.*]], [[REG12:%.*]]) = begin_apply [[REG10]]<T>([[REG0]]) : $@yield_once @convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @yields @in_guaranteed τ_0_0
+// CHECK:   [[REG13:%.*]] = alloc_stack $T
+// CHECK:   copy_addr [[REG11]] to [init] [[REG13]]
+// CHECK:   [[REG15:%.*]] = end_apply [[REG12]] as $()
+// CHECK:   [[REG16:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG17:%.*]] = apply [[REG16]]<T>([[REG13]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG13]]
+// CHECK:   dealloc_stack [[REG13]]
+// CHECK:   [[REG20:%.*]] = alloc_stack $T
+// CHECK:   [[REG21:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop3xvg : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @out τ_0_0
+// CHECK:   [[REG22:%.*]] = apply [[REG21]]<T>([[REG20]], [[REG0]]) : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @out τ_0_0
+// CHECK:   [[REG23:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG24:%.*]] = apply [[REG23]]<T>([[REG20]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG20]]
+// CHECK:   dealloc_stack [[REG20]]
+// CHECK:   [[REG27:%.*]] = tuple ()
+// CHECK:   return [[REG27]]
+// CHECK: }
+func testW1<T>(_ p: W<T>) {
+  use(p.prop1) // resolves to borrow
+  use(p.prop2) // resolves to _read
+  use(p.prop3) // resolves to getter
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis6testW2yyAA1WVyxGzlF : $@convention(thin) <T> (@inout W<T>) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*W<T>):
+// CHECK:   [[REG2:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG3:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop1xvz : $@convention(method) <τ_0_0> (@inout W<τ_0_0>) -> @inout τ_0_0
+// CHECK:   [[REG4:%.*]] = apply [[REG3]]<T>([[REG2]]) : $@convention(method) <τ_0_0> (@inout W<τ_0_0>) -> @inout τ_0_0
+// CHECK:   [[REG5:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG6:%.*]] = apply [[REG5]]<T>([[REG4]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   end_access [[REG2]]
+// CHECK:   [[REG8:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG9:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop2xvM : $@yield_once @convention(method) <τ_0_0> (@inout W<τ_0_0>) -> @yields @inout τ_0_0
+// CHECK:   ([[REG10:%.*]], [[REG11:%.*]]) = begin_apply [[REG9]]<T>([[REG8]]) : $@yield_once @convention(method) <τ_0_0> (@inout W<τ_0_0>) -> @yields @inout τ_0_0
+// CHECK:   [[REG12:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG13:%.*]] = apply [[REG12]]<T>([[REG10]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG14:%.*]] = end_apply [[REG11]] as $()
+// CHECK:   end_access [[REG8]]
+// CHECK:   [[REG16:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG17:%.*]] = alloc_stack $T
+// CHECK:   [[REG18:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop3xvg : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @out τ_0_0
+// CHECK:   [[REG19:%.*]] = apply [[REG18]]<T>([[REG17]], [[REG16]]) : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @out τ_0_0
+// CHECK:   [[REG20:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG21:%.*]] = apply [[REG20]]<T>([[REG17]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG22:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop3xvs : $@convention(method) <τ_0_0> (@in τ_0_0, @inout W<τ_0_0>) -> ()
+// CHECK:   [[REG23:%.*]] = apply [[REG22]]<T>([[REG17]], [[REG16]]) : $@convention(method) <τ_0_0> (@in τ_0_0, @inout W<τ_0_0>) -> ()
+// CHECK:   end_access [[REG16]]
+// CHECK:   dealloc_stack [[REG17]]
+// CHECK: }
+func testW2<T>(_ p: inout W<T>) {
+  mutate(&p.prop1) // resolves to mutate
+  mutate(&p.prop2) // resolves to _modify
+  mutate(&p.prop3) // resolves to get, set, _modify
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis6testW3yyAA1WVyxGzlF : $@convention(thin) <T> (@inout W<T>) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*W<T>):
+// CHECK:   [[REG2:%.*]] = begin_access [read] [unknown] [[REG0]]
+// CHECK:   [[REG3:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop1xvb : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @guaranteed_address τ_0_0
+// CHECK:   [[REG4:%.*]] = apply [[REG3]]<T>([[REG2]]) : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @guaranteed_address τ_0_0
+// CHECK:   [[REG5:%.*]] = alloc_stack $T
+// CHECK:   copy_addr [[REG4]] to [init] [[REG5]]
+// CHECK:   end_access [[REG2]]
+// CHECK:   [[REG8:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG9:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop1xvz : $@convention(method) <τ_0_0> (@inout W<τ_0_0>) -> @inout τ_0_0
+// CHECK:   [[REG10:%.*]] = apply [[REG9]]<T>([[REG8]]) : $@convention(method) <τ_0_0> (@inout W<τ_0_0>) -> @inout τ_0_0
+// CHECK:   copy_addr [take] [[REG5]] to [[REG10]]
+// CHECK:   end_access [[REG8]]
+// CHECK:   dealloc_stack [[REG5]]
+// CHECK:   [[REG14:%.*]] = begin_access [read] [unknown] [[REG0]]
+// CHECK:   [[REG15:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop2xvr : $@yield_once @convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @yields @in_guaranteed τ_0_0
+// CHECK:   ([[REG16:%.*]], [[REG17:%.*]]) = begin_apply [[REG15]]<T>([[REG14]]) : $@yield_once @convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @yields @in_guaranteed τ_0_0
+// CHECK:   [[REG18:%.*]] = alloc_stack $T
+// CHECK:   copy_addr [[REG16]] to [init] [[REG18]]
+// CHECK:   [[REG20:%.*]] = end_apply [[REG17]] as $()
+// CHECK:   end_access [[REG14]]
+// CHECK:   [[REG22:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG23:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop2xvM : $@yield_once @convention(method) <τ_0_0> (@inout W<τ_0_0>) -> @yields @inout τ_0_0
+// CHECK:   ([[REG24:%.*]], [[REG25:%.*]]) = begin_apply [[REG23]]<T>([[REG22]]) : $@yield_once @convention(method) <τ_0_0> (@inout W<τ_0_0>) -> @yields @inout τ_0_0
+// CHECK:   copy_addr [take] [[REG18]] to [[REG24]]
+// CHECK:   [[REG27:%.*]] = end_apply [[REG25]] as $()
+// CHECK:   end_access [[REG22]]
+// CHECK:   dealloc_stack [[REG18]]
+// CHECK:   [[REG30:%.*]] = begin_access [read] [unknown] [[REG0]]
+// CHECK:   [[REG31:%.*]] = alloc_stack $T
+// CHECK:   [[REG32:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop3xvg : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @out τ_0_0
+// CHECK:   [[REG33:%.*]] = apply [[REG32]]<T>([[REG31]], [[REG30]]) : $@convention(method) <τ_0_0> (@in_guaranteed W<τ_0_0>) -> @out τ_0_0
+// CHECK:   end_access [[REG30]]
+// CHECK:   [[REG35:%.*]] = begin_access [modify] [unknown] [[REG0]]
+// CHECK:   [[REG36:%.*]] = function_ref @$s25borrow_accessor_synthesis1WV5prop3xvs : $@convention(method) <τ_0_0> (@in τ_0_0, @inout W<τ_0_0>) -> ()
+// CHECK:   [[REG37:%.*]] = apply [[REG36]]<T>([[REG31]], [[REG35]]) : $@convention(method) <τ_0_0> (@in τ_0_0, @inout W<τ_0_0>) -> ()
+// CHECK:   end_access [[REG35]]
+// CHECK:   dealloc_stack [[REG31]]
+// CHECK: }
+func testW3<T>(_ p: inout W<T>) {
+  p.prop1 = p.prop1
+  p.prop2 = p.prop2
+  p.prop3 = p.prop3
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis7testNC1yyAA2NCVyxGlF : $@convention(thin) <T> (@in_guaranteed NC<T>) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*NC<T>):
+// CHECK:   [[REG2:%.*]] = mark_unresolved_non_copyable_value [no_consume_or_assign] [[REG0]]
+// CHECK:   [[REG3:%.*]] = function_ref @$s25borrow_accessor_synthesis2NCVAARi_zrlE5prop1xvb : $@convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed NC<τ_0_0>) -> @guaranteed_address τ_0_0
+// CHECK:   [[REG4:%.*]] = apply [[REG3]]<T>([[REG2]]) : $@convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed NC<τ_0_0>) -> @guaranteed_address τ_0_0
+// CHECK:   [[REG5:%.*]] = alloc_stack $T
+// CHECK:   copy_addr [[REG4]] to [init] [[REG5]]
+// CHECK:   [[REG7:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG8:%.*]] = apply [[REG7]]<T>([[REG5]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG5]]
+// CHECK:   dealloc_stack [[REG5]]
+// CHECK:   [[REG11:%.*]] = function_ref @$s25borrow_accessor_synthesis2NCVAARi_zrlE5prop2xvr : $@yield_once @convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed NC<τ_0_0>) -> @yields @in_guaranteed τ_0_0
+// CHECK:   ([[REG12:%.*]], [[REG13:%.*]]) = begin_apply [[REG11]]<T>([[REG2]]) : $@yield_once @convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed NC<τ_0_0>) -> @yields @in_guaranteed τ_0_0
+// CHECK:   [[REG14:%.*]] = alloc_stack $T
+// CHECK:   copy_addr [[REG12]] to [init] [[REG14]]
+// CHECK:   [[REG16:%.*]] = end_apply [[REG13]] as $()
+// CHECK:   [[REG17:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG18:%.*]] = apply [[REG17]]<T>([[REG14]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG14]]
+// CHECK:   dealloc_stack [[REG14]]
+// CHECK:   [[REG21:%.*]] = struct_element_addr [[REG2]], #NC.prop3
+// CHECK:   [[REG22:%.*]] = alloc_stack $T
+// CHECK:   copy_addr [[REG21]] to [init] [[REG22]]
+// CHECK:   [[REG24:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG25:%.*]] = apply [[REG24]]<T>([[REG22]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   destroy_addr [[REG22]]
+// CHECK:   dealloc_stack [[REG22]]
+// CHECK:   [[REG28:%.*]] = tuple ()
+// CHECK:   return [[REG28]]
+// CHECK: }
+func testNC1<T>(_ p: borrowing NC<T>) {
+  use(p.prop1) // resolves to borrow
+  use(p.prop2) // resolves to _read
+  use(p.prop3) // resolves to stored property
+}
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis7testNC2yyAA2NCVyxGzlF : $@convention(thin) <T> (@inout NC<T>) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*NC<T>):
+// CHECK:   [[REG2:%.*]] = mark_unresolved_non_copyable_value [consumable_and_assignable] [[REG0]]
+// CHECK:   [[REG3:%.*]] = begin_access [modify] [unknown] [[REG2]]
+// CHECK:   [[REG4:%.*]] = function_ref @$s25borrow_accessor_synthesis2NCVAARi_zrlE5prop1xvz : $@convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (@inout NC<τ_0_0>) -> @inout τ_0_0
+// CHECK:   [[REG5:%.*]] = apply [[REG4]]<T>([[REG3]]) : $@convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (@inout NC<τ_0_0>) -> @inout τ_0_0
+// CHECK:   [[REG6:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG7:%.*]] = apply [[REG6]]<T>([[REG5]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   end_access [[REG3]]
+// CHECK:   [[REG9:%.*]] = begin_access [modify] [unknown] [[REG2]]
+// CHECK:   [[REG10:%.*]] = function_ref @$s25borrow_accessor_synthesis2NCVAARi_zrlE5prop2xvM : $@yield_once @convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (@inout NC<τ_0_0>) -> @yields @inout τ_0_0
+// CHECK:   ([[REG11:%.*]], [[REG12:%.*]]) = begin_apply [[REG10]]<T>([[REG9]]) : $@yield_once @convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (@inout NC<τ_0_0>) -> @yields @inout τ_0_0
+// CHECK:   [[REG13:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG14:%.*]] = apply [[REG13]]<T>([[REG11]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG15:%.*]] = end_apply [[REG12]] as $()
+// CHECK:   end_access [[REG9]]
+// CHECK:   [[REG17:%.*]] = begin_access [modify] [unknown] [[REG2]]
+// CHECK:   [[REG18:%.*]] = struct_element_addr [[REG17]], #NC.prop3
+// CHECK:   [[REG19:%.*]] = function_ref @$s25borrow_accessor_synthesis6mutateyyxzRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   [[REG20:%.*]] = apply [[REG19]]<T>([[REG18]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@inout τ_0_0) -> ()
+// CHECK:   end_access [[REG17]]
+// CHECK: }
+func testNC2<T>(_ p: inout NC<T>) {
+  mutate(&p.prop1) // resolves to mutate
+  mutate(&p.prop2) // resolves to _modify
+  mutate(&p.prop3) // resolves to stored property
+}
+
+public protocol Container: ~Copyable {
+  associatedtype Element: ~Copyable
+  subscript(index: Int) -> Element { get set }
+}
+
+public struct RigidWrapper<T: ~Copyable>: Container & ~Copyable {
+  var _element: T
+
+  public subscript(index: Int) -> T {
+    borrow {
+      return _element
+    }
+    mutate {
+      return &_element
+    }
+  }
+}
+
+// CHECK: sil [ossa] @$s25borrow_accessor_synthesis12RigidWrapperVAARi_zrlEyxSicib : $@convention(method) <T where T : ~Copyable> (Int, @in_guaranteed RigidWrapper<T>) -> @guaranteed_address T {
+// CHECK: bb0(%0 : $Int, %1 : $*RigidWrapper<T>):
+// CHECK:   %4 = mark_unresolved_non_copyable_value [no_consume_or_assign] %1
+// CHECK:   %5 = struct_element_addr %4, #RigidWrapper._element
+// CHECK:   return %5
+// CHECK: }
+
+// CHECK: sil private [transparent] [thunk] [ossa] @$s25borrow_accessor_synthesis12RigidWrapperVyxGAA9ContainerAARi_zrlAaEPy7ElementQzSicirTW : $@yield_once @convention(witness_method: Container) <τ_0_0 where τ_0_0 : ~Copyable> @substituted <τ_0_0, τ_0_1> (Int, @in_guaranteed τ_0_0) -> @yields @in_guaranteed τ_0_1 for <RigidWrapper<τ_0_0>, τ_0_0> {
+// CHECK: bb0([[REG0:%.*]] : $Int, [[REG1:%.*]] : $*RigidWrapper<τ_0_0>):
+// CHECK:   [[REG2:%.*]] = function_ref @$s25borrow_accessor_synthesis12RigidWrapperVAARi_zrlEyxSicir : $@yield_once @convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (Int, @in_guaranteed RigidWrapper<τ_0_0>) -> @yields @in_guaranteed τ_0_0
+// CHECK:   ([[REG3:%.*]], [[REG4:%.*]]) = begin_apply [[REG2]]<τ_0_0>([[REG0]], [[REG1]]) : $@yield_once @convention(method) <τ_0_0 where τ_0_0 : ~Copyable> (Int, @in_guaranteed RigidWrapper<τ_0_0>) -> @yields @in_guaranteed τ_0_0
+// CHECK:   yield [[REG3]], resume bb1, unwind bb2
+// CHECK: bb1:
+// CHECK:   [[REG6:%.*]] = end_apply [[REG4]] as $()
+// CHECK:   [[REG7:%.*]] = tuple ()
+// CHECK:   return [[REG7]]
+// CHECK: bb2:
+// CHECK:   abort_apply [[REG4]]
+// CHECK:   unwind
+// CHECK: }
+
+// CHECK: sil hidden [ossa] @$s25borrow_accessor_synthesis13testContaineryyx_SitAA0E0RzlF : $@convention(thin) <T where T : Container> (@in_guaranteed T, Int) -> () {
+// CHECK: bb0([[REG0:%.*]] : $*T, [[REG1:%.*]] : $Int):
+// CHECK:   [[REG4:%.*]] = witness_method $T, #Container.subscript!read : <Self where Self : Container, Self : ~Copyable> (Self) -> (Int) -> () : $@yield_once @convention(witness_method: Container) <τ_0_0 where τ_0_0 : Container, τ_0_0 : ~Copyable> (Int, @in_guaranteed τ_0_0) -> @yields @in_guaranteed τ_0_0.Element
+// CHECK:   ([[REG5:%.*]], [[REG6:%.*]]) = begin_apply [[REG4]]<T>([[REG1]], [[REG0]]) : $@yield_once @convention(witness_method: Container) <τ_0_0 where τ_0_0 : Container, τ_0_0 : ~Copyable> (Int, @in_guaranteed τ_0_0) -> @yields @in_guaranteed τ_0_0.Element
+// CHECK:   [[REG7:%.*]] = mark_unresolved_non_copyable_value [no_consume_or_assign] [[REG5]]
+// CHECK:   [[REG8:%.*]] = function_ref @$s25borrow_accessor_synthesis3useyyxRi_zlF : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG9:%.*]] = apply [[REG8]]<T.Element>([[REG7]]) : $@convention(thin) <τ_0_0 where τ_0_0 : ~Copyable> (@in_guaranteed τ_0_0) -> ()
+// CHECK:   [[REG10:%.*]] = end_apply [[REG6]] as $()
+// CHECK:   [[REG11:%.*]] = tuple ()
+// CHECK:   return [[REG11]]
+// CHECK: }
+func testContainer<T: Container>(_ c: T, _ index: Int) {
+  use(c[index]) // resolved to subscript.read which maybe synthesized using borrow accessor for conformance
+}
diff --git a/test/Sema/borrow_and_mutate_accessors.swift b/test/Sema/borrow_and_mutate_accessors.swift
index 2e22978fc22ce..9cf9bb40f88a3 100644
--- a/test/Sema/borrow_and_mutate_accessors.swift
+++ b/test/Sema/borrow_and_mutate_accessors.swift
@@ -9,6 +9,34 @@ class Klass {
 
 struct Struct {
   var _i: Int = 0
+  var _k: Klass
+
+  var k1: Klass {
+    consuming borrow { // expected-error{{a 'borrow' accessor cannot be declared consuming}}
+      return _k
+    }
+    consuming mutate { // expected-error{{a 'mutate' accessor cannot be declared consuming}}
+      return &_k
+    }
+  }
+
+  var k2: Klass {
+    mutating borrow { // expected-error{{mutating ownership modifier is not yet supported on a 'borrow' accessor}}
+      return _k
+    }
+    nonmutating mutate { // expected-error{{nonmutating ownership modifier is not yet supported on a 'mutate' accessor}}
+      return &_k // expected-error{{'&' may only be used to pass an argument to inout parameter}}
+    }
+  }
+
+  var k3: Klass {
+    nonmutating borrow {
+      return _k
+    }
+    mutating mutate {
+      return &_k
+    }
+  }
 }
 
 extension Klass {