diff --git a/test/IRGen/async_wasm.swift b/test/IRGen/async_wasm.swift
index 933bbe58afcb2..cd27584748d78 100644
--- a/test/IRGen/async_wasm.swift
+++ b/test/IRGen/async_wasm.swift
@@ -1,5 +1,5 @@
 // RUN: %target-swift-frontend -primary-file %S/async.swift -enable-builtin-module -emit-ir  -disable-availability-checking | %FileCheck %s --check-prefix=NOTAIL
-// TODO(katei): %target-swift-frontend -primary-file %S/async.swift -enable-builtin-module -emit-ir  -disable-availability-checking -Xcc -mtail-call | %FileCheck %s --check-prefix=TAIL
+// RUN: %target-swift-frontend -primary-file %S/async.swift -enable-builtin-module -emit-ir  -disable-availability-checking -Xcc -mtail-call | %FileCheck %s --check-prefix=TAIL
 
 // REQUIRES: concurrency && CPU=wasm32
 
@@ -11,3 +11,11 @@
 // NOTAIL-NOT: @swift_task_alloc
 // NOTAIL-NOT: musttail call
 // NOTAIL: call swiftcc void @swift_task_future_wait_throwing(ptr {{.*}}, ptr {{.*}}, ptr {{.*}}, ptr {{.*}}, ptr {{.*}})
+
+// TAIL: "$s5async1fyyYaF"
+// TAIL: "$s5async1gyyYaKF"
+// TAIL: "$s5async1hyyS2iYbXEF"
+
+// TAIL: define{{.*}} swifttailcc void @"$s5async8testThisyyBonYaF"(ptr swiftasync %0{{.*}}
+// TAIL-NOT: @swift_task_alloc
+// TAIL: musttail call swifttailcc void @swift_task_future_wait_throwing(ptr {{.*}}, ptr {{.*}}, ptr {{.*}}, ptr {{.*}}, ptr {{.*}})
diff --git a/test/IRGen/async_wasm_tailcall.swift b/test/IRGen/async_wasm_tailcall.swift
new file mode 100644
index 0000000000000..b7bacc65ecaff
--- /dev/null
+++ b/test/IRGen/async_wasm_tailcall.swift
@@ -0,0 +1,34 @@
+// Verify that async coroutine splitting on Wasm uses musttail/return_call
+// with the tail-call feature and regular calls without it.
+
+// IR-level checks:
+// RUN: %target-swift-frontend %s -emit-ir -module-name test -disable-availability-checking | %FileCheck %s --check-prefix=NOTAIL
+// RUN: %target-swift-frontend %s -emit-ir -module-name test -disable-availability-checking -Xcc -mtail-call | %FileCheck %s --check-prefix=TAIL
+
+// Assembly-level checks:
+// RUN: %target-swift-frontend %s -S -module-name test -disable-availability-checking -Xcc -mtail-call | %FileCheck %s --check-prefix=TAIL-ASM
+// RUN: %target-swift-frontend %s -S -module-name test -disable-availability-checking | %FileCheck %s --check-prefix=NOTAIL-ASM
+
+// REQUIRES: concurrency
+// REQUIRES: CPU=wasm32
+
+func callee() async -> Int { return 42 }
+
+public func caller() async -> Int {
+  return await callee()
+}
+
+// Without -mtail-call: async functions use swiftcc, no musttail
+// NOTAIL: define {{.*}}swiftcc void @"$s4test6callerSiyYaF"(ptr swiftasync
+// NOTAIL-NOT: musttail call
+
+// With -mtail-call: async functions use swifttailcc with musttail
+// TAIL: define {{.*}}swifttailcc void @"$s4test6callerSiyYaF"(ptr swiftasync
+// TAIL: musttail call swifttailcc void
+
+// Assembly with -mtail-call: return_call Wasm instruction
+// TAIL-ASM: return_call
+
+// Assembly without -mtail-call: no return_call Wasm instruction
+// NOTAIL-ASM: .functype
+// NOTAIL-ASM-NOT: return_call
diff --git a/test/embedded/concurrency-tailcall.swift b/test/embedded/concurrency-tailcall.swift
new file mode 100644
index 0000000000000..67857b4059fac
--- /dev/null
+++ b/test/embedded/concurrency-tailcall.swift
@@ -0,0 +1,38 @@
+// Verify that embedded async coroutine splitting on Wasm uses
+// musttail/return_call with the tail-call feature and regular calls without it.
+
+// IR-level checks:
+// RUN: %target-swift-frontend -enable-experimental-feature Embedded -parse-as-library -module-name test %s -emit-ir | %FileCheck %s --check-prefix=NOTAIL
+// RUN: %target-swift-frontend -enable-experimental-feature Embedded -parse-as-library -module-name test %s -emit-ir -Xcc -mtail-call | %FileCheck %s --check-prefix=TAIL
+
+// Assembly-level checks:
+// RUN: %target-swift-frontend -enable-experimental-feature Embedded -parse-as-library -module-name test %s -S -Xcc -mtail-call | %FileCheck %s --check-prefix=TAIL-ASM
+// RUN: %target-swift-frontend -enable-experimental-feature Embedded -parse-as-library -module-name test %s -S | %FileCheck %s --check-prefix=NOTAIL-ASM
+
+// REQUIRES: swift_in_compiler
+// REQUIRES: optimized_stdlib
+// REQUIRES: OS=wasip1
+// REQUIRES: swift_feature_Embedded
+
+import _Concurrency
+
+func callee() async -> Int { return 42 }
+
+public func caller() async -> Int {
+  return await callee()
+}
+
+// Without -mtail-call: async functions use swiftcc, no musttail
+// NOTAIL: define {{.*}}swiftcc void @"$e4test6callerSiyYaF"(ptr swiftasync
+// NOTAIL-NOT: musttail call
+
+// With -mtail-call: async functions use swifttailcc with musttail
+// TAIL: define {{.*}}swifttailcc void @"$e4test6callerSiyYaF"(ptr swiftasync
+// TAIL: musttail call swifttailcc void
+
+// Assembly with -mtail-call: return_call Wasm instruction
+// TAIL-ASM: return_call
+
+// Assembly without -mtail-call: no return_call Wasm instruction
+// NOTAIL-ASM: .functype
+// NOTAIL-ASM-NOT: return_call