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
@@ -189,5 +189,35 @@
 __attribute__((clang_builtin_alias(__builtin_elementwise_sin)))
 double4 sin(double4);
 
+// trunc builtins
+#ifdef __HLSL_ENABLE_16_BIT
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+half trunc(half);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+half2 trunc(half2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+half3 trunc(half3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+half4 trunc(half4);
+#endif
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc))) float
+trunc(float);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+float2 trunc(float2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+float3 trunc(float3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+float4 trunc(float4);
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc))) double
+trunc(double);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+double2 trunc(double2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+double3 trunc(double3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_trunc)))
+double4 trunc(double4);
+
 } // namespace hlsl
 #endif //_HLSL_HLSL_INTRINSICS_H_
diff --git a/clang/test/CodeGenHLSL/builtins/trunc.hlsl b/clang/test/CodeGenHLSL/builtins/trunc.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenHLSL/builtins/trunc.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.trunc.f16(
+// NO_HALF: define noundef float @"?test_trunc_half@@YA$halff@$halff@@Z"(
+// NO_HALF: call float @llvm.trunc.f32(
+half test_trunc_half ( half p0 ) {
+  return trunc ( p0 );
+}
+// CHECK: define noundef <2 x half> @
+// CHECK: call <2 x half> @llvm.trunc.v2f16
+// NO_HALF: define noundef <2 x float> @"?test_trunc_float2@@YAT?$__vector@M$01@__clang@@T12@@Z"(
+// NO_HALF: call <2 x float> @llvm.trunc.v2f32(
+half2 test_trunc_half2 ( half2 p0 ) {
+  return trunc ( p0 );
+}
+// CHECK: define noundef <3 x half> @
+// CHECK: call <3 x half> @llvm.trunc.v3f16
+// NO_HALF: define noundef <3 x float> @"?test_trunc_float3@@YAT?$__vector@M$02@__clang@@T12@@Z"(
+// NO_HALF: call <3 x float> @llvm.trunc.v3f32(
+half3 test_trunc_half3 ( half3 p0 ) {
+  return trunc ( p0 );
+}
+// CHECK: define noundef <4 x half> @
+// CHECK: call <4 x half> @llvm.trunc.v4f16
+// NO_HALF: define noundef <4 x float> @"?test_trunc_float4@@YAT?$__vector@M$03@__clang@@T12@@Z"(
+// NO_HALF: call <4 x float> @llvm.trunc.v4f32(
+half4 test_trunc_half4 ( half4 p0 ) {
+  return trunc ( p0 );
+}
+
+// CHECK: define noundef float @
+// CHECK: call float @llvm.trunc.f32(
+float test_trunc_float ( float p0 ) {
+  return trunc ( p0 );
+}
+// CHECK: define noundef <2 x float> @
+// CHECK: call <2 x float> @llvm.trunc.v2f32
+float2 test_trunc_float2 ( float2 p0 ) {
+  return trunc ( p0 );
+}
+// CHECK: define noundef <3 x float> @
+// CHECK: call <3 x float> @llvm.trunc.v3f32
+float3 test_trunc_float3 ( float3 p0 ) {
+  return trunc ( p0 );
+}
+// CHECK: define noundef <4 x float> @
+// CHECK: call <4 x float> @llvm.trunc.v4f32
+float4 test_trunc_float4 ( float4 p0 ) {
+  return trunc ( p0 );
+}