diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index 3a43b1edcaba37..c965945d88b79a 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -256,16 +256,18 @@ static bool replaceCoroEndAsync(AnyCoroEndInst *End) {
   // Insert the return instruction.
   Builder.SetInsertPoint(End);
   Builder.CreateRetVoid();
-  InlineFunctionInfo FnInfo;
 
   // Remove the rest of the block, by splitting it into an unreachable block.
   auto *BB = End->getParent();
   BB->splitBasicBlock(End);
   BB->getTerminator()->eraseFromParent();
 
-  auto InlineRes = InlineFunction(*MustTailCall, FnInfo);
-  assert(InlineRes.isSuccess() && "Expected inlining to succeed");
-  (void)InlineRes;
+  if (MustTailCallFunc->getCallingConv() != CallingConv::SwiftTail) {
+    InlineFunctionInfo FnInfo;
+    auto InlineRes = InlineFunction(*MustTailCall, FnInfo);
+    assert(InlineRes.isSuccess() && "Expected inlining to succeed");
+    (void)InlineRes;
+  }
 
   // We have cleaned up the coro.end block above.
   return false;
@@ -1882,8 +1884,11 @@ static void splitAsyncCoroutine(Function &F, coro::Shape &Shape,
     auto *TailCall = coro::createMustTailCall(Suspend->getDebugLoc(), Fn, TTI,
                                               FnArgs, Builder);
     Builder.CreateRetVoid();
-    InlineFunctionInfo FnInfo;
-    (void)InlineFunction(*TailCall, FnInfo);
+
+    if (Fn->getCallingConv() != CallingConv::SwiftTail) {
+      InlineFunctionInfo FnInfo;
+      (void)InlineFunction(*TailCall, FnInfo);
+    }
 
     // Replace the lvm.coro.async.resume intrisic call.
     replaceAsyncResumeFunction(Suspend, Continuation);
diff --git a/llvm/test/Transforms/Coroutines/coro-async-c-cc.ll b/llvm/test/Transforms/Coroutines/coro-async-c-cc.ll
new file mode 100644
index 00000000000000..ca10181fabd029
--- /dev/null
+++ b/llvm/test/Transforms/Coroutines/coro-async-c-cc.ll
@@ -0,0 +1,39 @@
+; RUN: opt < %s -O0 -S | FileCheck --check-prefixes=CHECK %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@0 = internal constant { i32, i32 } { i32 trunc (i64 sub (i64 ptrtoint (ptr @craSH to i64), i64 ptrtoint (ptr getelementptr inbounds ({ i32, i32 }, ptr @0, i32 0, i32 1) to i64)) to i32), i32 64 }
+
+define dso_local void @af_suspend_fn(ptr %0, i64 %1, ptr %2) #0 {
+  ret void
+}
+
+; Make sure that this test case does not crash and produce a split function.
+; CHECK: craSH.resume.0
+
+define dso_local void @craSH(ptr %0) #0 {
+  %2 = call token @llvm.coro.id.async(i32 64, i32 8, i32 0, ptr @0)
+  %3 = call ptr @llvm.coro.begin(token %2, ptr null)
+  %4 = getelementptr inbounds { ptr, { ptr, ptr }, i64, { ptr, i1 }, i64, i64 }, ptr poison, i32 0, i32 0
+  %5 = call ptr @llvm.coro.async.resume()
+  store ptr %5, ptr %4, align 8
+  %6 = call { ptr, ptr, ptr } (i32, ptr, ptr, ...) @llvm.coro.suspend.async.sl_p0p0p0s(i32 0, ptr %5, ptr @ctxt_proj_fn, ptr @af_suspend_fn, ptr poison, i64 -1, ptr poison)
+  ret void
+}
+
+define dso_local ptr @ctxt_proj_fn(ptr %0) #0 {
+  ret ptr %0
+}
+
+declare { ptr, ptr, ptr } @llvm.coro.suspend.async.sl_p0p0p0s(i32, ptr, ptr, ...) #1
+
+declare token @llvm.coro.id.async(i32, i32, i32, ptr) #2
+
+declare ptr @llvm.coro.begin(token, ptr writeonly) #2
+
+declare ptr @llvm.coro.async.resume() #1
+
+attributes #0 = { "target-features"="+adx,+aes,+avx,+avx2,+bmi,+bmi2,+clflushopt,+clwb,+clzero,+crc32,+cx16,+cx8,+f16c,+fma,+fsgsbase,+fxsr,+invpcid,+lzcnt,+mmx,+movbe,+mwaitx,+pclmul,+pku,+popcnt,+prfchw,+rdpid,+rdpru,+rdrnd,+rdseed,+sahf,+sha,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+sse4a,+ssse3,+vaes,+vpclmulqdq,+wbnoinvd,+x87,+xsave,+xsavec,+xsaveopt,+xsaves" }
+attributes #1 = { nomerge nounwind }
+attributes #2 = { nounwind }
diff --git a/llvm/test/Transforms/Coroutines/coro-async-mutually-recursive.ll b/llvm/test/Transforms/Coroutines/coro-async-mutually-recursive.ll
new file mode 100644
index 00000000000000..4931fe998daa60
--- /dev/null
+++ b/llvm/test/Transforms/Coroutines/coro-async-mutually-recursive.ll
@@ -0,0 +1,158 @@
+; RUN: opt < %s -passes='default<O2>' -S | FileCheck --check-prefixes=CHECK %s
+; RUN: opt < %s -O0 -S | FileCheck --check-prefixes=CHECK-O0 %s
+
+
+; CHECK-NOT: llvm.coro.suspend.async
+; CHECK-O0-NOT: llvm.coro.suspend.async
+
+; This test used to crash during updating the call graph in coro splitting.
+
+target datalayout = "p:64:64:64"
+
+%swift.async_func_pointer = type <{ i32, i32 }>
+
+@"$s1d3fooyySbYaFTu" = hidden global %swift.async_func_pointer <{ i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s1d3fooyySbYaF" to i64), i64 ptrtoint (ptr @"$s1d3fooyySbYaFTu" to i64)) to i32), i32 16 }>
+@"$s1d3baryySbYaFTu" = hidden global %swift.async_func_pointer <{ i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s1d3baryySbYaF" to i64), i64 ptrtoint (ptr @"$s1d3baryySbYaFTu" to i64)) to i32), i32 16 }>
+
+define swifttailcc void @"$s1d3fooyySbYaF"(ptr swiftasync %0, i1 %1) {
+entry:
+  %2 = alloca ptr, align 8
+  %c.debug = alloca i1, align 8
+  %3 = call token @llvm.coro.id.async(i32 16, i32 16, i32 0, ptr @"$s1d3fooyySbYaFTu")
+  %4 = call ptr @llvm.coro.begin(token %3, ptr null)
+  store ptr %0, ptr %2, align 8
+  call void @llvm.memset.p0.i64(ptr align 8 %c.debug, i8 0, i64 1, i1 false)
+  store i1 %1, ptr %c.debug, align 8
+  call void asm sideeffect "", "r"(ptr %c.debug)
+  %5 = load i32, ptr getelementptr inbounds (%swift.async_func_pointer, ptr @"$s1d3baryySbYaFTu", i32 0, i32 1), align 8
+  %6 = zext i32 %5 to i64
+  %7 = call swiftcc ptr @swift_task_alloc(i64 %6) #4
+  call void @llvm.lifetime.start.p0(i64 -1, ptr %7)
+  %8 = load ptr, ptr %2, align 8
+  %9 = getelementptr inbounds <{ ptr, ptr }>, ptr %7, i32 0, i32 0
+  store ptr %8, ptr %9, align 8
+  %10 = call ptr @llvm.coro.async.resume()
+  %11 = getelementptr inbounds <{ ptr, ptr }>, ptr %7, i32 0, i32 1
+  store ptr %10, ptr %11, align 8
+  %12 = call { ptr } (i32, ptr, ptr, ...) @llvm.coro.suspend.async.sl_p0s(i32 0, ptr %10, ptr @__swift_async_resume_project_context, ptr @"$s1d3fooyySbYaF.0", ptr @"$s1d3baryySbYaF", ptr %7, i1 %1)
+  %13 = extractvalue { ptr } %12, 0
+  %14 = call ptr @__swift_async_resume_project_context(ptr %13)
+  store ptr %14, ptr %2, align 8
+  call swiftcc void @swift_task_dealloc(ptr %7) #4
+  call void @llvm.lifetime.end.p0(i64 -1, ptr %7)
+  %15 = load ptr, ptr %2, align 8
+  %16 = getelementptr inbounds <{ ptr, ptr }>, ptr %15, i32 0, i32 1
+  %17 = load ptr, ptr %16, align 8
+  %18 = load ptr, ptr %2, align 8
+  %19 = call i1 (ptr, i1, ...) @llvm.coro.end.async(ptr %4, i1 false, ptr @"$s1d3fooyySbYaF.0.1", ptr %17, ptr %18)
+  unreachable
+}
+
+declare token @llvm.coro.id.async(i32, i32, i32, ptr) #1
+
+declare void @llvm.trap() #2
+
+declare ptr @llvm.coro.begin(token, ptr) #1
+
+declare void @llvm.memset.p0.i64(ptr nocapture, i8, i64, i1 immarg) #3
+
+define hidden swifttailcc void @"$s1d3baryySbYaF"(ptr swiftasync %0, i1 %1) {
+entry:
+  %2 = alloca ptr, align 8
+  %c.debug = alloca i1, align 8
+  %3 = call token @llvm.coro.id.async(i32 16, i32 16, i32 0, ptr @"$s1d3baryySbYaFTu")
+  %4 = call ptr @llvm.coro.begin(token %3, ptr null)
+  store ptr %0, ptr %2, align 8
+  call void @llvm.memset.p0.i64(ptr align 8 %c.debug, i8 0, i64 1, i1 false)
+  store i1 %1, ptr %c.debug, align 8
+  call void asm sideeffect "", "r"(ptr %c.debug)
+  br i1 %1, label %5, label %17
+
+5:                                                ; preds = %entry
+  %6 = xor i1 %1, true
+  %7 = load i32, ptr getelementptr inbounds (%swift.async_func_pointer, ptr @"$s1d3fooyySbYaFTu", i32 0, i32 1), align 8
+  %8 = zext i32 %7 to i64
+  %9 = call swiftcc ptr @swift_task_alloc(i64 %8) #4
+  call void @llvm.lifetime.start.p0(i64 -1, ptr %9)
+  %10 = load ptr, ptr %2, align 8
+  %11 = getelementptr inbounds <{ ptr, ptr }>, ptr %9, i32 0, i32 0
+  store ptr %10, ptr %11, align 8
+  %12 = call ptr @llvm.coro.async.resume()
+  %13 = getelementptr inbounds <{ ptr, ptr }>, ptr %9, i32 0, i32 1
+  store ptr %12, ptr %13, align 8
+  %14 = call { ptr } (i32, ptr, ptr, ...) @llvm.coro.suspend.async.sl_p0s(i32 0, ptr %12, ptr @__swift_async_resume_project_context, ptr @"$s1d3baryySbYaF.0.2", ptr @"$s1d3fooyySbYaF", ptr %9, i1 %6)
+  %15 = extractvalue { ptr } %14, 0
+  %16 = call ptr @__swift_async_resume_project_context(ptr %15)
+  store ptr %16, ptr %2, align 8
+  call swiftcc void @swift_task_dealloc(ptr %9) #4
+  call void @llvm.lifetime.end.p0(i64 -1, ptr %9)
+  br label %18
+
+17:                                               ; preds = %entry
+  br label %18
+
+18:                                               ; preds = %5, %17
+  %19 = load ptr, ptr %2, align 8
+  %20 = getelementptr inbounds <{ ptr, ptr }>, ptr %19, i32 0, i32 1
+  %21 = load ptr, ptr %20, align 8
+  %22 = load ptr, ptr %2, align 8
+  %23 = call i1 (ptr, i1, ...) @llvm.coro.end.async(ptr %4, i1 false, ptr @"$s1d3baryySbYaF.0", ptr %21, ptr %22)
+  unreachable
+}
+
+declare swiftcc ptr @swift_task_alloc(i64) #4
+
+declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #5
+
+declare ptr @llvm.coro.async.resume() #6
+
+define linkonce_odr hidden ptr @__swift_async_resume_project_context(ptr %0) #7 {
+entry:
+  %1 = load ptr, ptr %0, align 8
+  %2 = call ptr @llvm.swift.async.context.addr()
+  store ptr %1, ptr %2, align 8
+  ret ptr %1
+}
+
+declare ptr @llvm.swift.async.context.addr() #1
+
+define internal swifttailcc void @"$s1d3fooyySbYaF.0"(ptr %0, ptr %1, i1 %2) #8 {
+entry:
+  musttail call swifttailcc void %0(ptr swiftasync %1, i1 %2)
+  ret void
+}
+
+declare { ptr } @llvm.coro.suspend.async.sl_p0s(i32, ptr, ptr, ...) #6
+
+declare swiftcc void @swift_task_dealloc(ptr) #4
+
+declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #5
+
+define internal swifttailcc void @"$s1d3fooyySbYaF.0.1"(ptr %0, ptr %1) #8 {
+entry:
+  musttail call swifttailcc void %0(ptr swiftasync %1)
+  ret void
+}
+
+declare i1 @llvm.coro.end.async(ptr, i1, ...) #1
+
+define internal swifttailcc void @"$s1d3baryySbYaF.0"(ptr %0, ptr %1) #8 {
+entry:
+  musttail call swifttailcc void %0(ptr swiftasync %1)
+  ret void
+}
+
+define internal swifttailcc void @"$s1d3baryySbYaF.0.2"(ptr %0, ptr %1, i1 %2) #8 {
+entry:
+  musttail call swifttailcc void %0(ptr swiftasync %1, i1 %2)
+  ret void
+}
+
+attributes #1 = { nounwind }
+attributes #2 = { cold noreturn nounwind }
+attributes #3 = { nocallback nofree nounwind willreturn}
+attributes #4 = { nounwind }
+attributes #5 = { nocallback nofree nosync nounwind willreturn }
+attributes #6 = { nomerge nounwind }
+attributes #7 = { alwaysinline nounwind }
+attributes #8 = { alwaysinline nounwind }
diff --git a/llvm/test/Transforms/Coroutines/swift-async-dbg.ll b/llvm/test/Transforms/Coroutines/swift-async-dbg.ll
index 74edf7a3f3a540..a78bcdf0ddee23 100644
--- a/llvm/test/Transforms/Coroutines/swift-async-dbg.ll
+++ b/llvm/test/Transforms/Coroutines/swift-async-dbg.ll
@@ -1,13 +1,13 @@
-; RUN: opt -mtriple='arm64-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s
-; RUN: opt -mtriple='x86_64' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s
-; RUN: opt -mtriple='i386-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s --check-prefix=NOENTRY
-; RUN: opt -mtriple='armv7-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s --check-prefix=NOENTRY
+; RUN: opt -mtriple='arm64-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg),always-inline' -o - | FileCheck %s
+; RUN: opt -mtriple='x86_64' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg),always-inline' -o - | FileCheck %s
+; RUN: opt -mtriple='i386-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg),always-inline' -o - | FileCheck %s --check-prefix=NOENTRY
+; RUN: opt -mtriple='armv7-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg),always-inline' -o - | FileCheck %s --check-prefix=NOENTRY
 
 ;; Replicate those tests with non-instruction debug markers.
-; RUN: opt --try-experimental-debuginfo-iterators -mtriple='arm64-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s
-; RUN: opt --try-experimental-debuginfo-iterators -mtriple='x86_64' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s
-; RUN: opt --try-experimental-debuginfo-iterators -mtriple='i386-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s --check-prefix=NOENTRY
-; RUN: opt --try-experimental-debuginfo-iterators -mtriple='armv7-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg)' -o - | FileCheck %s --check-prefix=NOENTRY
+; RUN: opt --try-experimental-debuginfo-iterators -mtriple='arm64-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg),always-inline' -o - | FileCheck %s
+; RUN: opt --try-experimental-debuginfo-iterators -mtriple='x86_64' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg),always-inline' -o - | FileCheck %s
+; RUN: opt --try-experimental-debuginfo-iterators -mtriple='i386-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg),always-inline' -o - | FileCheck %s --check-prefix=NOENTRY
+; RUN: opt --try-experimental-debuginfo-iterators -mtriple='armv7-' %s -S -passes='module(coro-early),cgscc(coro-split,simplifycfg),always-inline' -o - | FileCheck %s --check-prefix=NOENTRY
 
 ; NOENTRY-NOT: OP_llvm_entry_value
 
@@ -93,29 +93,29 @@ define swifttailcc void @coroutineA(ptr swiftasync %arg) !dbg !48 {
 @coroutineBTu = global <{i32, i32}> <{ i32 trunc (i64 sub (i64 ptrtoint (ptr @"coroutineB" to i64), i64 ptrtoint (ptr @"coroutineBTu" to i64)) to i32), i32 16 }>, align 8
 @coroutineATu = global <{i32, i32}> <{ i32 trunc (i64 sub (i64 ptrtoint (ptr @"coroutineA" to i64), i64 ptrtoint (ptr @"coroutineATu" to i64)) to i32), i32 16 }>, align 8
 
-define weak_odr hidden ptr @__swift_async_resume_get_context(ptr %arg) !dbg !64 {
+define weak_odr hidden ptr @__swift_async_resume_get_context(ptr %arg) alwaysinline !dbg !64 {
   ret ptr %arg, !dbg !65
 }
-define hidden swifttailcc void @coroutineA.1(ptr %arg, i64 %arg1, i64 %arg2, ptr %arg3) !dbg !66 {
+define hidden swifttailcc void @coroutineA.1(ptr %arg, i64 %arg1, i64 %arg2, ptr %arg3) alwaysinline !dbg !66 {
   musttail call swifttailcc void @swift_task_switch(ptr swiftasync %arg3, ptr %arg, i64 %arg1, i64 %arg2), !dbg !67
   ret void, !dbg !67
 }
 
-define weak_odr hidden ptr @__swift_async_resume_project_context(ptr %arg) !dbg !68 {
+define weak_odr hidden ptr @__swift_async_resume_project_context(ptr %arg) alwaysinline !dbg !68 {
   %i1 = load ptr, ptr %arg, align 8, !dbg !69
   %i2 = call ptr @llvm.swift.async.context.addr(), !dbg !69
   store ptr %i1, ptr %i2, align 8, !dbg !69
   ret ptr %i1, !dbg !69
 }
-define hidden swifttailcc void @coroutineA.0(ptr %arg, ptr %arg1) !dbg !70 {
+define hidden swifttailcc void @coroutineA.0(ptr %arg, ptr %arg1) alwaysinline !dbg !70 {
   musttail call swifttailcc void %arg(ptr swiftasync %arg1), !dbg !71
   ret void, !dbg !71
 }
-define hidden swifttailcc void @coroutineA.0.1(ptr %arg, ptr %arg1) !dbg !72 {
+define hidden swifttailcc void @coroutineA.0.1(ptr %arg, ptr %arg1) alwaysinline !dbg !72 {
   musttail call swifttailcc void %arg(ptr swiftasync %arg1), !dbg !73
   ret void, !dbg !73
 }
-define swifttailcc void @coroutineB(ptr swiftasync %arg) !dbg !37 {
+define swifttailcc void @coroutineB(ptr swiftasync %arg) alwaysinline !dbg !37 {
   %i2 = call token @llvm.coro.id.async(i32 16, i32 16, i32 0, ptr nonnull @coroutineBTu)
   %i3 = call ptr @llvm.coro.begin(token %i2, ptr null)
   %i6 = getelementptr inbounds <{ ptr, ptr }>, ptr %arg, i64 0, i32 1, !dbg !42
@@ -123,7 +123,7 @@ define swifttailcc void @coroutineB(ptr swiftasync %arg) !dbg !37 {
   %i10 = call i1 (ptr, i1, ...) @llvm.coro.end.async(ptr %i3, i1 false, ptr nonnull @coroutineB.0, ptr %i712, ptr %arg), !dbg !42
   unreachable, !dbg !42
 }
-define hidden swifttailcc void @coroutineB.0(ptr %arg, ptr %arg1) !dbg !44 {
+define hidden swifttailcc void @coroutineB.0(ptr %arg, ptr %arg1) alwaysinline !dbg !44 {
   musttail call swifttailcc void %arg(ptr swiftasync %arg1), !dbg !47
   ret void, !dbg !47
 }