Index: clang/include/clang/AST/StmtCXX.h
===================================================================
--- clang/include/clang/AST/StmtCXX.h
+++ clang/include/clang/AST/StmtCXX.h
@@ -385,6 +385,12 @@
   VarDecl *getPromiseDecl() const {
     return cast<VarDecl>(cast<DeclStmt>(getPromiseDeclStmt())->getSingleDecl());
   }
+  /// Return true if the constructor of the promise wouldn't throw,
+  /// return false other wise.
+  bool isPromiseCtorNothrow() const;
+  /// Return true if the promise_type::unhandled_exception wouldn't throw,
+  /// return false other wise.
+  bool isOnExceptionNothrow() const;
 
   Stmt *getInitSuspendStmt() const {
     return getStoredStmts()[SubStmt::InitSuspend];
Index: clang/lib/AST/StmtCXX.cpp
===================================================================
--- clang/lib/AST/StmtCXX.cpp
+++ clang/lib/AST/StmtCXX.cpp
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/AST/StmtCXX.h"
+#include "clang/AST/ExprCXX.h"
 
 #include "clang/AST/ASTContext.h"
 
@@ -125,3 +126,30 @@
   std::copy(Args.ParamMoves.begin(), Args.ParamMoves.end(),
             const_cast<Stmt **>(getParamMoves().data()));
 }
+
+bool CoroutineBodyStmt::isPromiseCtorNothrow() const {
+  Expr *CtorExpr = getPromiseDecl()->getInit();
+  if (isa<ExprWithCleanups>(CtorExpr))
+    CtorExpr = cast<ExprWithCleanups>(CtorExpr)->getSubExpr();
+  if (!isa<CXXConstructExpr>(CtorExpr))
+    // Unimaged pattern. Return false conservatively.
+    return false;
+
+  auto *Ctor = cast<CXXConstructExpr>(CtorExpr)->getConstructor();
+  return isNoexceptExceptionSpec(Ctor->getExceptionSpecType());
+}
+bool CoroutineBodyStmt::isOnExceptionNothrow() const {
+  Stmt *ExceptionHandler = getExceptionHandler();
+  if (!ExceptionHandler)
+    return true;
+  Expr *OnExceptionCall = cast<Expr>(ExceptionHandler);
+  if (isa<ExprWithCleanups>(OnExceptionCall))
+    OnExceptionCall = cast<ExprWithCleanups>(OnExceptionCall)->getSubExpr();
+  if (!isa<CallExpr>(OnExceptionCall))
+    // Unimaged pattern. Return false conservatively.
+    return false;
+  auto *UnhandledException = cast<CallExpr>(OnExceptionCall)->getDirectCallee();
+  assert(UnhandledException &&
+         "The Call to promise_type::unhandled_exception is not direct call.\n");
+  return isNoexceptExceptionSpec(UnhandledException->getExceptionSpecType());
+}
\ No newline at end of file
Index: clang/lib/CodeGen/CGCoroutine.cpp
===================================================================
--- clang/lib/CodeGen/CGCoroutine.cpp
+++ clang/lib/CodeGen/CGCoroutine.cpp
@@ -541,6 +541,23 @@
 }
 
 void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
+  // A coroutine would generate following codes:
+  // ```
+  //    promise-type promise promise-constructor-arguments ;
+  //    try {
+  //        co_await promise.initial_suspend();
+  //        function-body
+  //    } catch (...) {
+  //        promise.unhandled_exception();
+  //    }
+  //    co_await promise.final_suspend();
+  //  ```
+  //  promise_type::final_suspend is guranteed to be noexcept. So if the
+  //  constructor of promise_type and unhandled_exception() are guranteed
+  //  to be no throw, we could mark the coroutine as no throw.
+  if (S.isPromiseCtorNothrow() && S.isOnExceptionNothrow())
+    CurFn->addFnAttr(llvm::Attribute::NoUnwind);
+
   auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
   auto &TI = CGM.getContext().getTargetInfo();
   unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
Index: clang/test/CodeGenCoroutines/coro-nounwind.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCoroutines/coro-nounwind.cpp
@@ -0,0 +1,72 @@
+// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -triple=x86_64-pc-windows-msvc18.0.0 -emit-llvm %s -o - -fexceptions -fcxx-exceptions -disable-llvm-passes | FileCheck %s
+// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -triple=x86_64-unknown-linux-gnu -emit-llvm -o - %s -fexceptions -fcxx-exceptions -disable-llvm-passes | FileCheck --check-prefix=CHECK-LINUX %s
+
+#include "Inputs/coroutine.h"
+
+namespace coro = std::experimental::coroutines_v1;
+
+struct coro_nothrow_t {
+  struct promise_type {
+    coro_nothrow_t get_return_object() {
+      coro::coroutine_handle<promise_type>{};
+      return {};
+    }
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() noexcept { return {}; }
+    void return_void() {}
+    void unhandled_exception() noexcept;
+  };
+};
+
+// CHECK: define dso_local i8 @"?foo@@YA?AUcoro_nothrow_t{{.*}}#[[FOOATTRNUM:[0-9]+]]
+// CHECK-LINUX: define dso_local void @_Z3foov{{.*}}#[[FOOATTRNUM:[0-9]+]]
+
+coro_nothrow_t foo() {
+  co_return;
+}
+
+struct coro_ctor_maythrow_t {
+  struct promise_type {
+    coro_ctor_maythrow_t get_return_object() {
+      coro::coroutine_handle<promise_type>{};
+      return {};
+    }
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() noexcept { return {}; }
+    void return_void() {}
+    void unhandled_exception() noexcept;
+    promise_type();
+  };
+};
+
+// CHECK: define dso_local i8 @"?bar@@YA?AUcoro_ctor_maythrow_t{{.*}}#[[BARATTRNUM:[0-9]+]]
+// CHECK-LINUX: define dso_local void @_Z3barv() #[[BARATTRNUM:[0-9]+]]
+coro_ctor_maythrow_t bar() {
+  co_return;
+}
+
+struct coro_onexception_maythrow_t {
+  struct promise_type {
+    coro_onexception_maythrow_t get_return_object() {
+      coro::coroutine_handle<promise_type>{};
+      return {};
+    }
+    coro::suspend_never initial_suspend() { return {}; }
+    coro::suspend_never final_suspend() noexcept { return {}; }
+    void return_void() {}
+    void unhandled_exception();
+  };
+};
+
+// CHECK: define dso_local i8 @"?baz@@YA?AUcoro_onexception_maythrow_t{{.*}}#[[BAZATTRNUM:[0-9]+]]
+// CHECK-LINUX: define dso_local void @_Z3bazv() #[[BAZATTRNUM:[0-9]+]]
+
+// CHECK: attributes #[[FOOATTRNUM]] = {{.*}}nounwind
+// CHECK-NOT: attributes #[[BARATTRNUM]] = {{.*}}nounwind
+// CHECK-NOT: attributes #[[BAZATTRNUM]] = {{.*}}nounwind
+// CHECK-LINUX: attributes #[[FOOATTRNUM]] = {{.*}}nounwind
+// CHECK-LINUX-NOT: attributes #[[BARATTRNUM]] = {{.*}}nounwind
+// CHECK-LINUX-NOT: attributes #[[BAZATTRNUM]] = {{.*}}nounwind
+coro_onexception_maythrow_t baz() {
+  co_return;
+}
\ No newline at end of file