Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -1775,8 +1775,9 @@
 }
 
 def NoInline : DeclOrStmtAttr {
-  let Spellings = [GCC<"noinline">, CXX11<"clang", "noinline">,
-                   C2x<"clang", "noinline">, Declspec<"noinline">];
+  let Spellings = [Keyword<"__noinline__">, GCC<"noinline">,
+                   CXX11<"clang", "noinline">, C2x<"clang", "noinline">,
+                   Declspec<"noinline">];
   let Accessors = [Accessor<"isClangNoInline", [CXX11<"clang", "noinline">,
                                                 C2x<"clang", "noinline">]>];
   let Documentation = [NoInlineDocs];
Index: clang/include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticParseKinds.td
+++ clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -86,6 +86,9 @@
   "type nullability specifier %0 is a Clang extension">,
   InGroup<DiagGroup<"nullability-extension">>;
 
+def ext_cuda_noinline_keyword : Extension<
+  "__noinline__ keyword is a Clang extension for CUDA/HIP">, DefaultIgnore;
+
 def err_empty_enum : Error<"use of empty enum">;
 
 def ext_ident_list_in_param : Extension<
Index: clang/include/clang/Basic/Features.def
===================================================================
--- clang/include/clang/Basic/Features.def
+++ clang/include/clang/Basic/Features.def
@@ -270,5 +270,8 @@
 
 FEATURE(cxx_abi_relative_vtable, LangOpts.CPlusPlus && LangOpts.RelativeCXXABIVTables)
 
+// CUDA/HIP Extensions
+EXTENSION(cuda_noinline_keyword, LangOpts.CUDA)
+
 #undef EXTENSION
 #undef FEATURE
Index: clang/include/clang/Basic/TokenKinds.def
===================================================================
--- clang/include/clang/Basic/TokenKinds.def
+++ clang/include/clang/Basic/TokenKinds.def
@@ -599,6 +599,9 @@
 // C++ for OpenCL s2.3.1: addrspace_cast operator
 KEYWORD(addrspace_cast              , KEYOPENCLCXX)
 
+// CUDA/HIP function attributes
+KEYWORD(__noinline__                , KEYCUDA)
+
 // OpenMP Type Traits
 UNARY_EXPR_OR_TYPE_TRAIT(__builtin_omp_required_simd_align, OpenMPRequiredSimdAlign, KEYALL)
 
Index: clang/include/clang/Parse/Parser.h
===================================================================
--- clang/include/clang/Parse/Parser.h
+++ clang/include/clang/Parse/Parser.h
@@ -2824,6 +2824,7 @@
   void ParseOpenCLKernelAttributes(ParsedAttributes &attrs);
   void ParseOpenCLQualifiers(ParsedAttributes &Attrs);
   void ParseNullabilityTypeSpecifiers(ParsedAttributes &attrs);
+  void ParseCUDAFunctionAttributes(ParsedAttributes &attrs);
 
   VersionTuple ParseVersionTuple(SourceRange &Range);
   void ParseAvailabilityAttribute(IdentifierInfo &Availability,
Index: clang/lib/Basic/IdentifierTable.cpp
===================================================================
--- clang/lib/Basic/IdentifierTable.cpp
+++ clang/lib/Basic/IdentifierTable.cpp
@@ -108,6 +108,7 @@
     KEYOPENCLCXX  = 0x400000,
     KEYMSCOMPAT   = 0x800000,
     KEYSYCL       = 0x1000000,
+    KEYCUDA       = 0x2000000,
     KEYALLCXX = KEYCXX | KEYCXX11 | KEYCXX20,
     KEYALL = (0x1ffffff & ~KEYNOMS18 &
               ~KEYNOOPENCL) // KEYNOMS18 and KEYNOOPENCL are used to exclude.
@@ -158,6 +159,8 @@
     return KS_Future;
   if (LangOpts.isSYCL() && (Flags & KEYSYCL))
     return KS_Enabled;
+  if (LangOpts.CUDA && (Flags & KEYCUDA))
+    return KS_Enabled;
   return KS_Disabled;
 }
 
Index: clang/lib/Parse/ParseDecl.cpp
===================================================================
--- clang/lib/Parse/ParseDecl.cpp
+++ clang/lib/Parse/ParseDecl.cpp
@@ -897,6 +897,18 @@
   }
 }
 
+void Parser::ParseCUDAFunctionAttributes(ParsedAttributes &attrs) {
+  while (Tok.is(tok::kw___noinline__)) {
+    IdentifierInfo *AttrName = Tok.getIdentifierInfo();
+    SourceLocation AttrNameLoc = ConsumeToken();
+    attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
+                 ParsedAttr::AS_Keyword);
+    if (getLangOpts().CUDA) {
+      Diag(Tok, diag::ext_cuda_noinline_keyword);
+    }
+  }
+}
+
 void Parser::ParseOpenCLQualifiers(ParsedAttributes &Attrs) {
   IdentifierInfo *AttrName = Tok.getIdentifierInfo();
   SourceLocation AttrNameLoc = Tok.getLocation();
@@ -3690,6 +3702,11 @@
       ParseOpenCLKernelAttributes(DS.getAttributes());
       continue;
 
+    // CUDA/HIP single token adornments.
+    case tok::kw___noinline__:
+      ParseCUDAFunctionAttributes(DS.getAttributes());
+      continue;
+
     // Nullability type specifiers.
     case tok::kw__Nonnull:
     case tok::kw__Nullable:
Index: clang/test/CodeGenCUDA/noinline.cu
===================================================================
--- /dev/null
+++ clang/test/CodeGenCUDA/noinline.cu
@@ -0,0 +1,30 @@
+// optimization is needed, otherwise by default all functions have noinline.
+
+// RUN: %clang_cc1 -triple nvptx-nvidia-cuda -fcuda-is-device \
+// RUN:     -O2 -emit-llvm -o - %s | FileCheck %s
+
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -fcuda-is-device \
+// RUN:     -O2 -emit-llvm -o - -x hip %s | FileCheck %s
+
+// RUN: %clang_cc1 -triple x86_64-unknown-gnu-linux \
+// RUN:     -O2 -emit-llvm -o - %s | FileCheck %s
+
+#include "Inputs/cuda.h"
+
+__noinline__ __device__ __host__ void fun1() {}
+
+__attribute__((noinline)) __device__ __host__ void fun2() {}
+
+__attribute__((__noinline__)) __device__ __host__ void fun3() {}
+
+[[gnu::__noinline__]] __device__ __host__ void fun4() {}
+
+__device__ __host__ void fun5() {}
+
+// CHECK: define{{.*}}@_Z4fun1v{{.*}}#[[ATTR1:[0-9]*]]
+// CHECK: define{{.*}}@_Z4fun2v{{.*}}#[[ATTR1:[0-9]*]]
+// CHECK: define{{.*}}@_Z4fun3v{{.*}}#[[ATTR1:[0-9]*]]
+// CHECK: define{{.*}}@_Z4fun4v{{.*}}#[[ATTR1:[0-9]*]]
+// CHECK: define{{.*}}@_Z4fun5v{{.*}}#[[ATTR2:[0-9]*]]
+// CHECK: attributes #[[ATTR1]] = {{.*}}noinline
+// CHECK-NOT: attributes #[[ATTR2]] = {{.*}}noinline
Index: clang/test/Lexer/has_extension.cu
===================================================================
--- /dev/null
+++ clang/test/Lexer/has_extension.cu
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -E -triple x86_64-linux-gnu %s -o - | FileCheck %s
+
+// CHECK: has_noinline_keyword
+#if __has_extension(cuda_noinline_keyword)
+int has_noinline_keyword();
+#else
+int no_noinine_keyword();
+#endif
Index: clang/test/SemaCUDA/noinline.cu
===================================================================
--- /dev/null
+++ clang/test/SemaCUDA/noinline.cu
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -fsyntax-only -verify=cuda %s
+// RUN: %clang_cc1 -fsyntax-only -verify=pedantic -pedantic %s
+// RUN: %clang_cc1 -fsyntax-only -verify=cpp -x c++ %s
+
+// cuda-no-diagnostics
+
+__noinline__ void fun1() { } // cpp-error {{unknown type name '__noinline__'}}
+// pedantic-warning@-1 {{__noinline__ keyword is a Clang extension for CUDA/HIP}}
+
+__attribute__((noinline)) void fun2() { }
+__attribute__((__noinline__)) void fun3() { }
+[[gnu::__noinline__]] void fun4() { }