diff --git a/libs/vkd3d-shader/hlsl_codegen.c b/libs/vkd3d-shader/hlsl_codegen.c
index 36270b15..520ba20a 100644
--- a/libs/vkd3d-shader/hlsl_codegen.c
+++ b/libs/vkd3d-shader/hlsl_codegen.c
@@ -4925,6 +4925,14 @@ void hlsl_calculate_buffer_offsets(struct hlsl_ctx *ctx)
     }
 }
 
+static unsigned int get_max_cbuffer_reg_index(struct hlsl_ctx *ctx)
+{
+    if (hlsl_version_ge(ctx, 5, 1))
+        return UINT_MAX;
+
+    return 13;
+}
+
 static void allocate_buffers(struct hlsl_ctx *ctx)
 {
     struct hlsl_buffer *buffer;
@@ -4956,6 +4964,12 @@ static void allocate_buffers(struct hlsl_ctx *ctx)
             {
                 const struct hlsl_buffer *reserved_buffer = get_reserved_buffer(ctx,
                         reservation->reg_space, reservation->reg_index);
+                unsigned int max_index = get_max_cbuffer_reg_index(ctx);
+
+                if (buffer->reservation.reg_index > max_index)
+                    hlsl_error(ctx, &buffer->loc, VKD3D_SHADER_ERROR_HLSL_INVALID_RESERVATION,
+                            "Buffer reservation cb%u exceeds target's maximum (cb%u).",
+                            buffer->reservation.reg_index, max_index);
 
                 if (reserved_buffer && reserved_buffer != buffer)
                 {
@@ -4980,9 +4994,14 @@ static void allocate_buffers(struct hlsl_ctx *ctx)
             }
             else if (!reservation->reg_type)
             {
+                unsigned int max_index = get_max_cbuffer_reg_index(ctx);
                 while (get_reserved_buffer(ctx, 0, index))
                     ++index;
 
+                if (index > max_index)
+                    hlsl_error(ctx, &buffer->loc, VKD3D_SHADER_ERROR_HLSL_INVALID_RESERVATION,
+                        "Too many buffers allocated, target's maximum is %u.", max_index);
+
                 buffer->reg.space = 0;
                 buffer->reg.index = index;
                 if (hlsl_version_ge(ctx, 5, 1))
diff --git a/tests/hlsl/register-reservations-numeric.shader_test b/tests/hlsl/register-reservations-numeric.shader_test
index f5cb5f24..1e977271 100644
--- a/tests/hlsl/register-reservations-numeric.shader_test
+++ b/tests/hlsl/register-reservations-numeric.shader_test
@@ -433,7 +433,7 @@ probe (0, 0) rgba(2.0, 2.0, 2.0, 2.0)
 [require]
 shader model >= 4.0
 
-[pixel shader fail todo]
+[pixel shader fail]
 
 cbuffer buf : register(b0manymanyletters)
 {
@@ -451,7 +451,7 @@ float4 main() : sv_target
 
 % DXC fails during parsing.
 
-[pixel shader fail todo]
+[pixel shader fail]
 cbuffer buf : register(banana)
 {
     float a;
@@ -497,3 +497,452 @@ float4 main() : sv_target
 todo(glsl) draw quad
 if(sm<6) probe (0, 0) rgba(2.0, 2.0, 2.0, 2.0)
 if(sm>=6) probe (0, 0) rgba(0.5, 0.5, 0.5, 0.5)
+
+% cbuffer reservation limits.
+[pixel shader]
+cbuffer buf0 : register(b0)
+{
+    float a;
+};
+
+cbuffer buf1 : register(b1)
+{
+    float b;
+};
+
+cbuffer buf2 : register(b2)
+{
+    float c;
+};
+
+cbuffer buf3 : register(b3)
+{
+    float d;
+};
+
+cbuffer buf4 : register(b4)
+{
+    float e;
+};
+
+cbuffer buf5 : register(b5)
+{
+    float f;
+};
+
+cbuffer buf6 : register(b6)
+{
+    float g;
+};
+
+cbuffer buf7 : register(b7)
+{
+    float h;
+};
+
+cbuffer buf8 : register(b8)
+{
+    float i;
+};
+
+cbuffer buf9 : register(b9)
+{
+    float j;
+};
+
+cbuffer buf10 : register(b10)
+{
+    float k;
+};
+
+cbuffer buf11 : register(b11)
+{
+    float l;
+};
+
+cbuffer buf12 : register(b12)
+{
+    float m;
+};
+
+cbuffer buf13 : register(b13)
+{
+    float n;
+};
+
+float4 main() : sv_target
+{
+    return a * b * c * d * e * f * g * h * i * j * k * l * m * n;
+}
+
+[pixel shader fail(sm>=6)]
+// $Globals and $Params count towards the 14 cbuffer limit.
+float glob;
+
+cbuffer buf0 : register(b0)
+{
+    float a;
+};
+
+cbuffer buf1 : register(b1)
+{
+    float b;
+};
+
+cbuffer buf2 : register(b2)
+{
+    float c;
+};
+
+cbuffer buf3 : register(b3)
+{
+    float d;
+};
+
+cbuffer buf4 : register(b4)
+{
+    float e;
+};
+
+cbuffer buf5 : register(b5)
+{
+    float f;
+};
+
+cbuffer buf6 : register(b6)
+{
+    float g;
+};
+
+cbuffer buf7 : register(b7)
+{
+    float h;
+};
+
+cbuffer buf8 : register(b8)
+{
+    float i;
+};
+
+cbuffer buf9 : register(b9)
+{
+    float j;
+};
+
+cbuffer buf10 : register(b10)
+{
+    float k;
+};
+
+cbuffer buf11 : register(b11)
+{
+    float l;
+};
+
+float4 main(uniform float param) : sv_target
+{
+    return glob * param * a * b * c * d * e * f * g * h * i * j * k * l;
+}
+
+[pixel shader fail]
+float glob;
+
+cbuffer buf0 : register(b0)
+{
+    float a;
+};
+
+cbuffer buf1 : register(b1)
+{
+    float b;
+};
+
+cbuffer buf2 : register(b2)
+{
+    float c;
+};
+
+cbuffer buf3 : register(b3)
+{
+    float d;
+};
+
+cbuffer buf4 : register(b4)
+{
+    float e;
+};
+
+cbuffer buf5 : register(b5)
+{
+    float f;
+};
+
+cbuffer buf6 : register(b6)
+{
+    float g;
+};
+
+cbuffer buf7 : register(b7)
+{
+    float h;
+};
+
+cbuffer buf8 : register(b8)
+{
+    float i;
+};
+
+cbuffer buf9 : register(b9)
+{
+    float j;
+};
+
+cbuffer buf10 : register(b10)
+{
+    float k;
+};
+
+cbuffer buf11 : register(b11)
+{
+    float l;
+};
+
+cbuffer buf12 : register(b12)
+{
+    float m;
+};
+
+float4 main(uniform float param) : sv_target
+{
+    return glob * param * a * b * c * d * e * f * g * h * i * j * k * l * m;
+}
+
+[pixel shader fail todo]
+// Unused cbuffers still reserve their slot, and count towards the limit.
+float glob;
+
+cbuffer buf0 : register(b0)
+{
+    float a;
+};
+
+cbuffer buf1 : register(b1)
+{
+    float b;
+};
+
+cbuffer buf2 : register(b2)
+{
+    float c;
+};
+
+cbuffer buf3 : register(b3)
+{
+    float d;
+};
+
+cbuffer buf4 : register(b4)
+{
+    float e;
+};
+
+cbuffer buf5 : register(b5)
+{
+    float f;
+};
+
+cbuffer buf6 : register(b6)
+{
+    float g;
+};
+
+cbuffer buf7 : register(b7)
+{
+    float h;
+};
+
+cbuffer buf8 : register(b8)
+{
+    float i;
+};
+
+cbuffer buf9 : register(b9)
+{
+    float j;
+};
+
+cbuffer buf10 : register(b10)
+{
+    float k;
+};
+
+cbuffer buf11 : register(b11)
+{
+    float l;
+};
+
+cbuffer buf12 : register(b12)
+{
+    float m;
+};
+
+float4 main(uniform float param) : sv_target
+{
+    return glob * param * a * b * c * d * e * f * g * h * i * j * k * l;
+}
+
+[require]
+shader model >= 5.1
+
+[pixel shader fail(sm>=6)]
+// 5.1 and up have unlimited CBV slots.
+float glob;
+
+cbuffer buf0 : register(b0)
+{
+    float a;
+};
+
+cbuffer buf1 : register(b1)
+{
+    float b;
+};
+
+cbuffer buf2 : register(b2)
+{
+    float c;
+};
+
+cbuffer buf3 : register(b3)
+{
+    float d;
+};
+
+cbuffer buf4 : register(b4)
+{
+    float e;
+};
+
+cbuffer buf5 : register(b5)
+{
+    float f;
+};
+
+cbuffer buf6 : register(b6)
+{
+    float g;
+};
+
+cbuffer buf7 : register(b7)
+{
+    float h;
+};
+
+cbuffer buf8 : register(b8)
+{
+    float i;
+};
+
+cbuffer buf9 : register(b9)
+{
+    float j;
+};
+
+cbuffer buf10 : register(b10)
+{
+    float k;
+};
+
+cbuffer buf11 : register(b11)
+{
+    float l;
+};
+
+cbuffer buf12 : register(b12)
+{
+    float m;
+};
+
+float4 main(uniform float param) : sv_target
+{
+    return glob * param * a * b * c * d * e * f * g * h * i * j * k * l * m;
+}
+
+[pixel shader]
+// SM6 doesn't support uniform parameters (why??)
+float glob;
+
+cbuffer buf0 : register(b0)
+{
+    float a;
+};
+
+cbuffer buf1 : register(b1)
+{
+    float b;
+};
+
+cbuffer buf2 : register(b2)
+{
+    float c;
+};
+
+cbuffer buf3 : register(b3)
+{
+    float d;
+};
+
+cbuffer buf4 : register(b4)
+{
+    float e;
+};
+
+cbuffer buf5 : register(b5)
+{
+    float f;
+};
+
+cbuffer buf6 : register(b6)
+{
+    float g;
+};
+
+cbuffer buf7 : register(b7)
+{
+    float h;
+};
+
+cbuffer buf8 : register(b8)
+{
+    float i;
+};
+
+cbuffer buf9 : register(b9)
+{
+    float j;
+};
+
+cbuffer buf10 : register(b10)
+{
+    float k;
+};
+
+cbuffer buf11 : register(b11)
+{
+    float l;
+};
+
+cbuffer buf12 : register(b12)
+{
+    float m;
+};
+
+cbuffer buf13 : register(b13)
+{
+    float n;
+};
+
+float4 main() : sv_target
+{
+    return glob * a * b * c * d * e * f * g * h * i * j * k * l * m * n;
+}