diff --git a/lib/IRGen/GenFunc.cpp b/lib/IRGen/GenFunc.cpp
index 9fa62c75fc33f..9d09b0c833c9c 100644
--- a/lib/IRGen/GenFunc.cpp
+++ b/lib/IRGen/GenFunc.cpp
@@ -2158,7 +2158,9 @@ Optional<StackAddress> irgen::emitFunctionPartialApplication(
     HeapNonFixedOffsets offsets(IGF, layout);
     if (outType->isNoEscape()) {
       stackAddr = IGF.emitDynamicAlloca(
-          IGF.IGM.Int8Ty, layout.isFixedLayout() ? layout.emitSize(IGF.IGM) : offsets.getSize() , Alignment(16));
+          IGF.IGM.Int8Ty,
+          layout.isFixedLayout() ? layout.emitSize(IGF.IGM) : offsets.getSize(),
+          Alignment(16));
       stackAddr = stackAddr->withAddress(IGF.Builder.CreateElementBitCast(
           stackAddr->getAddress(), IGF.IGM.OpaqueTy));
       data = stackAddr->getAddress().getAddress();
diff --git a/lib/IRGen/GenOpaque.cpp b/lib/IRGen/GenOpaque.cpp
index d738bac6e4373..7a1f170762505 100644
--- a/lib/IRGen/GenOpaque.cpp
+++ b/lib/IRGen/GenOpaque.cpp
@@ -578,8 +578,11 @@ StackAddress IRGenFunction::emitDynamicAlloca(llvm::Type *eltTy,
     // MaximumAlignment.
     byteCount = alignUpToMaximumAlignment(IGM.SizeTy, byteCount);
     auto address = emitTaskAlloc(byteCount, align);
-    return {address, address.getAddress()};
-  // In coroutines, call llvm.coro.alloca.alloc.
+    auto stackAddress = StackAddress{address, address.getAddress()};
+    stackAddress = stackAddress.withAddress(
+        Builder.CreateElementBitCast(stackAddress.getAddress(), eltTy));
+    return stackAddress;
+    // In coroutines, call llvm.coro.alloca.alloc.
   } else if (isCoroutine()) {
     // NOTE: llvm does not support dynamic allocas in coroutines.
 
@@ -603,7 +606,11 @@ StackAddress IRGenFunction::emitDynamicAlloca(llvm::Type *eltTy,
     auto ptr = Builder.CreateIntrinsicCall(llvm::Intrinsic::coro_alloca_get,
                                            {allocToken});
 
-    return {Address(ptr, IGM.Int8Ty, align), allocToken};
+    auto stackAddress =
+        StackAddress{Address(ptr, IGM.Int8Ty, align), allocToken};
+    stackAddress = stackAddress.withAddress(
+        Builder.CreateElementBitCast(stackAddress.getAddress(), eltTy));
+    return stackAddress;
   }
 
   // Otherwise, use a dynamic alloca.
diff --git a/validation-test/IRGen/rdar109540863.swift b/validation-test/IRGen/rdar109540863.swift
new file mode 100644
index 0000000000000..2cc6004bde2fc
--- /dev/null
+++ b/validation-test/IRGen/rdar109540863.swift
@@ -0,0 +1,23 @@
+// RUN: %target-swift-frontend %s -disable-availability-checking -emit-ir | %FileCheck %s
+
+// REQUIRES: concurrency
+
+// CHECK: define {{.*}}@callee
+@_silgen_name("callee")
+func callee<each T : P>(_ ts: repeat each T) async {
+  (repeat (each ts).foo())
+}
+
+// CHECK: define {{.*}}@caller
+@_silgen_name("caller")
+func caller<each T1 : P>(t1: repeat each T1) async {
+  await callee(S(), repeat each t1)
+}
+
+struct S : P {
+  func foo() {
+  }
+}
+protocol P {
+  func foo()
+}