diff --git a/tools/qfcc/source/glsl-builtins.c b/tools/qfcc/source/glsl-builtins.c
index 2b6fa1858..6c7dbed40 100644
--- a/tools/qfcc/source/glsl-builtins.c
+++ b/tools/qfcc/source/glsl-builtins.c
@@ -232,122 +232,119 @@ type_t type_glsl_sampler = {
 
 static const char *glsl_Vulkan_vertex_vars =
 SRC_LINE
-"in int gl_VertexIndex;"        "\n"
-"in int gl_InstanceIndex;"      "\n"
-"in int gl_DrawID;"             "\n"
-"in int gl_BaseVertex;"         "\n"
-"in int gl_BaseInstance;"       "\n"
-"#ifdef GL_EXT_multiview"       "\n"
-"highp int gl_ViewIndex;"       "\n"
-"#endif"                        "\n"
-"out gl_PerVertex {"            "\n"
-"    vec4 gl_Position;"         "\n"
-"    float gl_PointSize;"       "\n"
-"    float gl_ClipDistance[];"  "\n"
-"    float gl_CullDistance[];"  "\n"
-"};"                            "\n";
+"layout (builtin=\"VertexIndex\") in int gl_VertexIndex;"               "\n"
+"layout (builtin=\"InstanceIndex\") in int gl_InstanceIndex;"           "\n"
+"#ifdef GL_EXT_multiview"                                               "\n"
+"layout (builtin=\"ViewIndex\") in highp int gl_ViewIndex;"             "\n"
+"#endif"                                                                "\n"
+"out gl_PerVertex {"                                                    "\n"
+"    layout (builtin=\"Position\") vec4 gl_Position;"                   "\n"
+"    layout (builtin=\"PointSize\") float gl_PointSize;"                "\n"
+"    layout (builtin=\"ClipDistance\") float gl_ClipDistance[];"        "\n"
+"    layout (builtin=\"CullDistance\") float gl_CullDistance[];"        "\n"
+"};"                                                                    "\n";
 
 //tesselation control
 static const char *glsl_tesselation_control_vars =
 SRC_LINE
-"in gl_PerVertex {"                     "\n"
-"    vec4 gl_Position;"                 "\n"
-"    float gl_PointSize;"               "\n"
-"    float gl_ClipDistance[];"          "\n"
-"    float gl_CullDistance[];"          "\n"
-"} gl_in[gl_MaxPatchVertices];"         "\n"
-"in int gl_PatchVerticesIn;"            "\n"
-"in int gl_PrimitiveID;"                "\n"
-"in int gl_InvocationID;"               "\n"
-"#ifdef GL_EXT_multiview"               "\n"
-"highp int gl_ViewIndex;"               "\n"
-"#endif"                                "\n"
-"out gl_PerVertex {"                    "\n"
-"    vec4 gl_Position;"                 "\n"
-"    float gl_PointSize;"               "\n"
-"    float gl_ClipDistance[];"          "\n"
-"    float gl_CullDistance[];"          "\n"
-"} gl_out[];"                           "\n"
-"patch out float gl_TessLevelOuter[4];" "\n"
-"patch out float gl_TessLevelInner[2];" "\n";
+"in gl_PerVertex {"                                                     "\n"
+"    layout (builtin=\"Position\") vec4 gl_Position;"                   "\n"
+"    layout (builtin=\"PointSize\") float gl_PointSize;"                "\n"
+"    layout (builtin=\"ClipDistance\") float gl_ClipDistance[];"        "\n"
+"    layout (builtin=\"CullDistance\") float gl_CullDistance[];"        "\n"
+"} gl_in[gl_MaxPatchVertices];"                                         "\n"
+"layout (builtin=\"PatchVertices\") in int gl_PatchVerticesIn;"         "\n"
+"layout (builtin=\"PrimitiveID\") in int gl_PrimitiveID;"               "\n"
+"layout (builtin=\"InvocationID\") in int gl_InvocationID;"             "\n"
+"#ifdef GL_EXT_multiview"                                               "\n"
+"layout (builtin=\"ViewIndex\") in highp int gl_ViewIndex;"             "\n"
+"#endif"                                                                "\n"
+"out gl_PerVertex {"                                                    "\n"
+"    layout (builtin=\"Position\") vec4 gl_Position;"                   "\n"
+"    layout (builtin=\"PointSize\") float gl_PointSize;"                "\n"
+"    layout (builtin=\"ClipDistance\") float gl_ClipDistance[];"        "\n"
+"    layout (builtin=\"CullDistance\") float gl_CullDistance[];"        "\n"
+"} gl_out[];"                                                           "\n"
+"layout (builtin=\"TessLevelOuter\") patch out float gl_TessLevelOuter[4];\n"
+"layout (builtin=\"TessLevelInner\") patch out float gl_TessLevelInner[2];\n";
 
 static const char *glsl_tesselation_evaluation_vars =
 SRC_LINE
-"in gl_PerVertex {"                     "\n"
-"    vec4 gl_Position;"                 "\n"
-"    float gl_PointSize;"               "\n"
-"    float gl_ClipDistance[];"          "\n"
-"    float gl_CullDistance[];"          "\n"
-"} gl_in[gl_MaxPatchVertices];"         "\n"
-"in int gl_PatchVerticesIn;"            "\n"
-"in int gl_PrimitiveID;"                "\n"
-"in vec3 gl_TessCoord;"                 "\n"
-"patch in float gl_TessLevelOuter[4];"  "\n"
-"patch in float gl_TessLevelInner[2];"  "\n"
-"#ifdef GL_EXT_multiview"               "\n"
-"highp int gl_ViewIndex;"               "\n"
-"#endif"                                "\n"
-"out gl_PerVertex {"                    "\n"
-"    vec4 gl_Position;"                 "\n"
-"    float gl_PointSize;"               "\n"
-"    float gl_ClipDistance[];"          "\n"
-"    float gl_CullDistance[];"          "\n"
-"};"                                    "\n";
+"in gl_PerVertex {"                                                     "\n"
+"    layout (builtin=\"Position\") vec4 gl_Position;"                   "\n"
+"    layout (builtin=\"PointSize\") float gl_PointSize;"                "\n"
+"    layout (builtin=\"ClipDistance\") float gl_ClipDistance[];"        "\n"
+"    layout (builtin=\"CullDistance\") float gl_CullDistance[];"        "\n"
+"} gl_in[gl_MaxPatchVertices];"                                         "\n"
+"layout (builtin=\"PatchVertices\") in int gl_PatchVerticesIn;"         "\n"
+"layout (builtin=\"PrimitiveID\") in int gl_PrimitiveID;"               "\n"
+"layout (builtin=\"TessCoord\") in vec3 gl_TessCoord;"                  "\n"
+"layout (builtin=\"TessLevelOuter\") patch in float gl_TessLevelOuter[4];" "\n"
+"layout (builtin=\"TessLevelInner\") patch in float gl_TessLevelInner[2];" "\n"
+"#ifdef GL_EXT_multiview"                                               "\n"
+"layout (builtin=\"ViewIndex\") in highp int gl_ViewIndex;"             "\n"
+"#endif"                                                                "\n"
+"out gl_PerVertex {"                                                    "\n"
+"    layout (builtin=\"Position\") vec4 gl_Position;"                   "\n"
+"    layout (builtin=\"PointSize\") float gl_PointSize;"                "\n"
+"    layout (builtin=\"ClipDistance\") float gl_ClipDistance[];"        "\n"
+"    layout (builtin=\"CullDistance\") float gl_CullDistance[];"        "\n"
+"};"                                                                    "\n";
 
 static const char *glsl_geometry_vars =
 SRC_LINE
-"in gl_PerVertex {"             "\n"
-"    vec4 gl_Position;"         "\n"
-"    float gl_PointSize;"       "\n"
-"    float gl_ClipDistance[];"  "\n"
-"    float gl_CullDistance[];"  "\n"
-"} gl_in[];"                    "\n"
-"in int gl_PrimitiveIDIn;"      "\n"
-"in int gl_InvocationID;"       "\n"
-"#ifdef GL_EXT_multiview"       "\n"
-"highp int gl_ViewIndex;"       "\n"
-"#endif"                        "\n"
-"out gl_PerVertex {"            "\n"
-"    vec4 gl_Position;"         "\n"
-"    float gl_PointSize;"       "\n"
-"    float gl_ClipDistance[];"  "\n"
-"    float gl_CullDistance[];"  "\n"
-"};"                            "\n"
-"out int gl_PrimitiveID;"       "\n"
-"out int gl_Layer;"             "\n"
-"out int gl_ViewportIndex;"     "\n";
+"in gl_PerVertex {"                                                     "\n"
+"    layout (builtin=\"Position\") vec4 gl_Position;"                   "\n"
+"    layout (builtin=\"PointSize\") float gl_PointSize;"                "\n"
+"    layout (builtin=\"ClipDistance\") float gl_ClipDistance[];"        "\n"
+"    layout (builtin=\"CullDistance\") float gl_CullDistance[];"        "\n"
+"} gl_in[];"                                                            "\n"
+"layout (builtin=\"PrimitiveID\") in int gl_PrimitiveIDIn;"             "\n"
+"layout (builtin=\"InvocationID\") in int gl_InvocationID;"             "\n"
+"#ifdef GL_EXT_multiview"                                               "\n"
+"layout (builtin=\"ViewIndex\") in highp int gl_ViewIndex;"             "\n"
+"#endif"                                                                "\n"
+"out gl_PerVertex {"                                                    "\n"
+"    layout (builtin=\"Position\") vec4 gl_Position;"                   "\n"
+"    layout (builtin=\"PointSize\") float gl_PointSize;"                "\n"
+"    layout (builtin=\"ClipDistance\") float gl_ClipDistance[];"        "\n"
+"    layout (builtin=\"CullDistance\") float gl_CullDistance[];"        "\n"
+"};"                                                                    "\n"
+"layout (builtin=\"PrimitiveID\") out int gl_PrimitiveID;"              "\n"
+"layout (builtin=\"Layer\") out int gl_Layer;"                          "\n"
+"layout (builtin=\"ViewportIndex\") out int gl_ViewportIndex;"          "\n";
 
 static const char *glsl_fragment_vars =
 SRC_LINE
-"in vec4 gl_FragCoord;"         "\n"
-"in bool gl_FrontFacing;"       "\n"
-"in float gl_ClipDistance[];"   "\n"
-"in float gl_CullDistance[];"   "\n"
-"in vec2 gl_PointCoord;"        "\n"
-"in int gl_PrimitiveID;"        "\n"
-"in int gl_SampleID;"           "\n"
-"in vec2 gl_SamplePosition;"    "\n"
-"in int gl_SampleMaskIn[];"     "\n"
-"in int gl_Layer;"              "\n"
-"in int gl_ViewportIndex;"      "\n"
-"in bool gl_HelperInvocation;"  "\n"
-"#ifdef GL_EXT_multiview"       "\n"
-"highp int gl_ViewIndex;"       "\n"
-"#endif"                        "\n"
-"out float gl_FragDepth;"       "\n"
-"out int gl_SampleMask[];"      "\n";
+"layout (builtin=\"FragCoord\") in vec4 gl_FragCoord;"                  "\n"
+"layout (builtin=\"FrontFacing\") in bool gl_FrontFacing;"              "\n"
+"layout (builtin=\"ClipDistance\") in float gl_ClipDistance[];"         "\n"
+"layout (builtin=\"CullDistance\") in float gl_CullDistance[];"         "\n"
+"layout (builtin=\"PointCoord\") in vec2 gl_PointCoord;"                "\n"
+"layout (builtin=\"PrimitiveID\") in int gl_PrimitiveID;"               "\n"
+"layout (builtin=\"SampleID\") in int gl_SampleID;"                     "\n"
+"layout (builtin=\"SamplePosition\") in vec2 gl_SamplePosition;"        "\n"
+"layout (builtin=\"SampleMask\") in int gl_SampleMaskIn[];"             "\n"
+"layout (builtin=\"Layer\") in int gl_Layer;"                           "\n"
+"layout (builtin=\"ViewportIndex\") in int gl_ViewportIndex;"           "\n"
+"layout (builtin=\"HelperInvocation\") in bool gl_HelperInvocation;"    "\n"
+"#ifdef GL_EXT_multiview"                                               "\n"
+"layout (builtin=\"ViewIndex\") in highp int gl_ViewIndex;"             "\n"
+"#endif"                                                                "\n"
+"layout (builtin=\"FragDepth\") out float gl_FragDepth;"                "\n"
+"layout (builtin=\"SampleMask\") out int gl_SampleMask[];"              "\n";
 
 static const char *glsl_compute_vars =
 SRC_LINE
-"// workgroup dimensions"           "\n"
-"in uvec3 gl_NumWorkGroups;"        "\n"
-"readonly uvec3 gl_WorkGroupSize;"  "\n"
-"// workgroup and invocation IDs"   "\n"
-"in uvec3 gl_WorkGroupID;"          "\n"
-"in uvec3 gl_LocalInvocationID;"    "\n"
-"// derived variables"              "\n"
-"in uvec3 gl_GlobalInvocationID;"   "\n"
-"in uint gl_LocalInvocationIndex;"  "\n";
+"// workgroup dimensions"                                               "\n"
+"layout (builtin=\"NumWorkgroups\") in uvec3 gl_NumWorkGroups;"         "\n"
+"layout (builtin=\"WorkgroupSize\") in uvec3 gl_WorkGroupSize;"         "\n"
+"// workgroup and invocation IDs"                                       "\n"
+"layout (builtin=\"WorkgroupId\") in uvec3 gl_WorkGroupID;"             "\n"
+"layout (builtin=\"LocalInvocationId\") in uvec3 gl_LocalInvocationID;" "\n"
+"// derived variables"                                                  "\n"
+"layout (builtin=\"GlobalInvocationId\") in uvec3 gl_GlobalInvocationID;""\n"
+"layout (builtin=\"LocalInvocationIndex\") in uint gl_LocalInvocationIndex;\n";
 
 static const char *glsl_system_constants =
 SRC_LINE
diff --git a/tools/qfcc/source/glsl-layout.c b/tools/qfcc/source/glsl-layout.c
index 7e3188d13..f4261dded 100644
--- a/tools/qfcc/source/glsl-layout.c
+++ b/tools/qfcc/source/glsl-layout.c
@@ -115,6 +115,14 @@ glsl_layout_packing (const layout_qual_t *qual, specifier_t spec,
 {
 }
 
+static void
+glsl_layout_builtin (const layout_qual_t *qual, specifier_t spec,
+					 const expr_t *qual_name, const expr_t *val)
+{
+	const char *name = "BuiltIn";
+	set_attribute (&spec.sym->attributes, name, val);
+}
+
 static void
 glsl_layout_location (const layout_qual_t *qual, specifier_t spec,
 					  const expr_t *qual_name, const expr_t *val)
@@ -260,6 +268,13 @@ glsl_layout_ignore (const layout_qual_t *qual, specifier_t spec,
 
 static bool sorted_layout_qualifiers;
 static layout_qual_t layout_qualifiers[] = {
+	{	.name = "builtin",
+		.apply = E(glsl_layout_builtin),
+		.obj_mask = D(var)|D(member),
+		.var_type = V(any),
+		.if_mask = I(in)|I(out),
+	},
+
 	{	.name = "shared",
 		.apply = A(glsl_layout_invalid_A),
 		.obj_mask = D(qual)|D(block),
diff --git a/tools/qfcc/source/glsl-parse.y b/tools/qfcc/source/glsl-parse.y
index 762c6727a..2b97c0f78 100644
--- a/tools/qfcc/source/glsl-parse.y
+++ b/tools/qfcc/source/glsl-parse.y
@@ -360,6 +360,7 @@ new_identifier
 primary_exprsssion
 	: variable_identifier	{ $$ = new_symbol_expr ($1); }
 	| VALUE
+	| STRING
 	| TRUE					{ $$ = new_bool_expr (true); }
 	| FALSE					{ $$ = new_bool_expr (false); }
 	| '(' expression ')'	{ $$ = paren_expr ($2); }