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
@@ -101,6 +101,36 @@
 __attribute__((clang_builtin_alias(__builtin_elementwise_ceil)))
 double4 ceil(double4);
 
+// floor builtins
+#ifdef __HLSL_ENABLE_16_BIT
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+half floor(half);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+half2 floor(half2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+half3 floor(half3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+half4 floor(half4);
+#endif
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor))) float
+floor(float);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+float2 floor(float2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+float3 floor(float3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+float4 floor(float4);
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor))) double
+floor(double);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+double2 floor(double2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+double3 floor(double3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+double4 floor(double4);
+
 // cos builtins
 #ifdef __HLSL_ENABLE_16_BIT
 __attribute__((clang_builtin_alias(__builtin_elementwise_cos))) half cos(half);
diff --git a/clang/test/CodeGenHLSL/builtins/floor.hlsl b/clang/test/CodeGenHLSL/builtins/floor.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenHLSL/builtins/floor.hlsl
@@ -0,0 +1,79 @@
+// 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
+
+using hlsl::floor;
+
+// CHECK: define noundef half @
+// CHECK: call half @llvm.floor.f16(
+// NO_HALF: define noundef float @"?test_floor_half@@YA$halff@$halff@@Z"(
+// NO_HALF: call float @llvm.floor.f32(float %0)
+half test_floor_half ( half p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <2 x half> @
+// CHECK: call <2 x half> @llvm.floor.v2f16(
+// NO_HALF: define noundef <2 x float> @"?test_floor_half2@@YAT?$__vector@$halff@$01@__clang@@T12@@Z"(
+// NO_HALF: call <2 x float> @llvm.floor.v2f32(
+half2 test_floor_half2 ( half2 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <3 x half> @
+// CHECK: call <3 x half> @llvm.floor.v3f16(
+// NO_HALF: define noundef <3 x float> @"?test_floor_half3@@YAT?$__vector@$halff@$02@__clang@@T12@@Z"(
+// NO_HALF: call <3 x float> @llvm.floor.v3f32(
+half3 test_floor_half3 ( half3 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <4 x half> @
+// CHECK: call <4 x half> @llvm.floor.v4f16(
+// NO_HALF: define noundef <4 x float> @"?test_floor_half4@@YAT?$__vector@$halff@$03@__clang@@T12@@Z"(
+// NO_HALF: call <4 x float> @llvm.floor.v4f32(
+half4 test_floor_half4 ( half4 p0 ) {
+  return floor ( p0 );
+}
+
+// CHECK: define noundef float @
+// CHECK: call float @llvm.floor.f32(
+float test_floor_float ( float p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <2 x float> @
+// CHECK: call <2 x float> @llvm.floor.v2f32(
+float2 test_floor_float2 ( float2 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <3 x float> @
+// CHECK: call <3 x float> @llvm.floor.v3f32(
+float3 test_floor_float3 ( float3 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <4 x float> @
+// CHECK: call <4 x float> @llvm.floor.v4f32(
+float4 test_floor_float4 ( float4 p0 ) {
+  return floor ( p0 );
+}
+
+// CHECK: define noundef double @
+// CHECK: call double @llvm.floor.f64(
+double test_floor_double ( double p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <2 x double> @
+// CHECK: call <2 x double> @llvm.floor.v2f64(
+double2 test_floor_double2 ( double2 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <3 x double> @
+// CHECK: call <3 x double> @llvm.floor.v3f64(
+double3 test_floor_double3 ( double3 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <4 x double> @
+// CHECK: call <4 x double> @llvm.floor.v4f64(
+double4 test_floor_double4 ( double4 p0 ) {
+  return floor ( p0 );
+}