diff --git a/clang/include/clang/Basic/Builtins.def b/clang/include/clang/Basic/Builtins.def
--- a/clang/include/clang/Basic/Builtins.def
+++ b/clang/include/clang/Basic/Builtins.def
@@ -659,6 +659,7 @@
 BUILTIN(__builtin_elementwise_max, "v.", "nct")
 BUILTIN(__builtin_elementwise_min, "v.", "nct")
 BUILTIN(__builtin_elementwise_ceil, "v.", "nct")
+BUILTIN(__builtin_elementwise_cos, "v.", "nct")
 BUILTIN(__builtin_elementwise_floor, "v.", "nct")
 BUILTIN(__builtin_elementwise_roundeven, "v.", "nct")
 BUILTIN(__builtin_elementwise_trunc, "v.", "nct")
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -3055,6 +3055,9 @@
   case Builtin::BI__builtin_elementwise_ceil:
     return RValue::get(
         emitUnaryBuiltin(*this, E, llvm::Intrinsic::ceil, "elt.ceil"));
+  case Builtin::BI__builtin_elementwise_cos:
+    return RValue::get(
+        emitUnaryBuiltin(*this, E, llvm::Intrinsic::cos, "elt.cos"));
   case Builtin::BI__builtin_elementwise_floor:
     return RValue::get(
         emitUnaryBuiltin(*this, E, llvm::Intrinsic::floor, "elt.floor"));
diff --git a/clang/lib/Headers/hlsl/hlsl_intrinsics.h b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
--- a/clang/lib/Headers/hlsl/hlsl_intrinsics.h
+++ b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
@@ -99,4 +99,25 @@
 __attribute__((clang_builtin_alias(__builtin_elementwise_ceil)))
 double4 ceil(double4);
 
+// cos builtins
+
+#ifdef __HLSL_ENABLE_16_BIT
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos))) half cos(half);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+half2 cos(half2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+half3 cos(half3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+half4 cos(half4);
+#endif
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos))) float
+cos(float);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+float2 cos(float2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+float3 cos(float3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+float4 cos(float4);
+
 #endif //_HLSL_HLSL_INTRINSICS_H_
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -2571,6 +2571,7 @@
   // These builtins restrict the element type to floating point
   // types only.
   case Builtin::BI__builtin_elementwise_ceil:
+  case Builtin::BI__builtin_elementwise_cos:
   case Builtin::BI__builtin_elementwise_floor:
   case Builtin::BI__builtin_elementwise_roundeven:
   case Builtin::BI__builtin_elementwise_trunc: {
diff --git a/clang/test/CodeGenHLSL/builtins/cos.hlsl b/clang/test/CodeGenHLSL/builtins/cos.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenHLSL/builtins/cos.hlsl
@@ -0,0 +1,56 @@
+// RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -fnative-half-type \
+// RUN:   -emit-llvm -disable-llvm-passes -O3 -o - | FileCheck %s
+// RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -emit-llvm -disable-llvm-passes \
+// RUN:   -D__HLSL_ENABLE_16_BIT -o - | FileCheck %s --check-prefix=NO_HALF
+
+// CHECK: define noundef half @
+// CHECK: call half @llvm.cos.f16(
+// NO_HALF: define noundef float @"?test_cos_half@@YA$halff@$halff@@Z"(
+// NO_HALF: call float @llvm.cos.f32(
+half test_cos_half ( half p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <2 x half> @
+// CHECK: call <2 x half> @llvm.cos.v2f16(
+// NO_HALF: define noundef <2 x float> @"?test_cos_float2@@YAT?$__vector@M$01@__clang@@T12@@Z"(
+// NO_HALF: call <2 x float> @llvm.cos.v2f32(
+half2 test_cos_half2 ( half2 p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <3 x half> @
+// CHECK: call <3 x half> @llvm.cos.v3f16(
+// NO_HALF: define noundef <3 x float> @"?test_cos_float3@@YAT?$__vector@M$02@__clang@@T12@@Z"(
+// NO_HALF: call <3 x float> @llvm.cos.v3f32(
+half3 test_cos_half3 ( half3 p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <4 x half> @
+// CHECK: call <4 x half> @llvm.cos.v4f16(
+// NO_HALF: define noundef <4 x float> @"?test_cos_float4@@YAT?$__vector@M$03@__clang@@T12@@Z"(
+// NO_HALF: call <4 x float> @llvm.cos.v4f32
+half4 test_cos_half4 ( half4 p0 ) {
+  return cos ( p0 );
+}
+
+// CHECK: define noundef float @
+// CHECK: call float @llvm.cos.f32(
+float test_cos_float(float p0) {
+  return cos(p0);
+}
+// CHECK: define noundef <2 x float> @
+// CHECK: call <2 x float> @llvm.cos.v2f32(
+float2 test_cos_float2(float2 p0) {
+  return cos(p0);
+}
+// CHECK: define noundef <3 x float> @
+// CHECK: call <3 x float> @llvm.cos.v3f32(
+float3 test_cos_float3(float3 p0) {
+  return cos(p0);
+}
+// CHECK: define noundef <4 x float> @
+// CHECK: call <4 x float> @llvm.cos.v4f32(
+float4 test_cos_float4(float4 p0) {
+  return cos(p0);
+}
\ No newline at end of file