diff --git a/dlls/d3dx9_36/d3dx9_36.spec b/dlls/d3dx9_36/d3dx9_36.spec
index 52fbe7cda57..e2e401c2594 100644
--- a/dlls/d3dx9_36/d3dx9_36.spec
+++ b/dlls/d3dx9_36/d3dx9_36.spec
@@ -147,7 +147,7 @@
 @ stub D3DXGatherFragmentsFromResourceW
 @ stub D3DXGenerateOutputDecl
 @ stub D3DXGeneratePMesh
-@ stub D3DXGetDeclLength
+@ stdcall D3DXGetDeclLength(ptr)
 @ stdcall D3DXGetDeclVertexSize(ptr long)
 @ stdcall D3DXGetDriverLevel(ptr)
 @ stdcall D3DXGetFVFVertexSize(long)
diff --git a/dlls/d3dx9_36/mesh.c b/dlls/d3dx9_36/mesh.c
index 12e26da0458..a6146fe8e9d 100644
--- a/dlls/d3dx9_36/mesh.c
+++ b/dlls/d3dx9_36/mesh.c
@@ -520,6 +520,22 @@ UINT WINAPI D3DXGetDeclVertexSize(const D3DVERTEXELEMENT9 *decl, DWORD stream_id
     return size;
 }
 
+/*************************************************************************
+ * D3DXGetDeclLength
+ */
+UINT WINAPI D3DXGetDeclLength(const D3DVERTEXELEMENT9 *decl)
+{
+    const D3DVERTEXELEMENT9 *element;
+
+    TRACE("decl %p\n", decl);
+
+    /* null decl results in exception on Windows XP */
+
+    for (element = decl; element->Stream != 0xff; ++element);
+
+    return element - decl;
+}
+
 /*************************************************************************
  * D3DXIntersectTri
  */
diff --git a/dlls/d3dx9_36/tests/mesh.c b/dlls/d3dx9_36/tests/mesh.c
index 619d667795e..e5a49bfe248 100644
--- a/dlls/d3dx9_36/tests/mesh.c
+++ b/dlls/d3dx9_36/tests/mesh.c
@@ -1407,6 +1407,56 @@ static void D3DXCreateSphereTest(void)
     DestroyWindow(wnd);
 }
 
+static void test_get_decl_length(void)
+{
+    static const D3DVERTEXELEMENT9 declaration1[] =
+    {
+        {0, 0, D3DDECLTYPE_FLOAT1, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {1, 0, D3DDECLTYPE_FLOAT2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {2, 0, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {3, 0, D3DDECLTYPE_FLOAT4, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {4, 0, D3DDECLTYPE_D3DCOLOR, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {5, 0, D3DDECLTYPE_UBYTE4, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {6, 0, D3DDECLTYPE_SHORT2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {7, 0, D3DDECLTYPE_SHORT4, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {8, 0, D3DDECLTYPE_UBYTE4N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {9, 0, D3DDECLTYPE_SHORT2N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {10, 0, D3DDECLTYPE_SHORT4N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {11, 0, D3DDECLTYPE_UDEC3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {12, 0, D3DDECLTYPE_DEC3N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {13, 0, D3DDECLTYPE_FLOAT16_2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {14, 0, D3DDECLTYPE_FLOAT16_4, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        D3DDECL_END(),
+    };
+    static const D3DVERTEXELEMENT9 declaration2[] =
+    {
+        {0, 8, D3DDECLTYPE_FLOAT1, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {1, 8, D3DDECLTYPE_FLOAT2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {2, 8, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {3, 8, D3DDECLTYPE_FLOAT4, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {4, 8, D3DDECLTYPE_D3DCOLOR, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {5, 8, D3DDECLTYPE_UBYTE4, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {6, 8, D3DDECLTYPE_SHORT2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {7, 8, D3DDECLTYPE_SHORT4, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {0, 8, D3DDECLTYPE_UBYTE4N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {1, 8, D3DDECLTYPE_SHORT2N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {2, 8, D3DDECLTYPE_SHORT4N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {3, 8, D3DDECLTYPE_UDEC3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {4, 8, D3DDECLTYPE_DEC3N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {5, 8, D3DDECLTYPE_FLOAT16_2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {6, 8, D3DDECLTYPE_FLOAT16_4, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        {7, 8, D3DDECLTYPE_FLOAT1, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0},
+        D3DDECL_END(),
+    };
+    UINT size;
+
+    size = D3DXGetDeclLength(declaration1);
+    ok(size == 15, "Got size %u, expected 15.\n", size);
+
+    size = D3DXGetDeclLength(declaration2);
+    ok(size == 16, "Got size %u, expected 16.\n", size);
+}
+
 static void test_get_decl_vertex_size(void)
 {
     static const D3DVERTEXELEMENT9 declaration1[] =
@@ -1488,6 +1538,7 @@ START_TEST(mesh)
     D3DXIntersectTriTest();
     D3DXCreateMeshTest();
     D3DXCreateSphereTest();
+    test_get_decl_length();
     test_get_decl_vertex_size();
     test_fvf_decl_conversion();
 }
diff --git a/include/d3dx9mesh.h b/include/d3dx9mesh.h
index 32d3947cc55..02dc7a96a08 100644
--- a/include/d3dx9mesh.h
+++ b/include/d3dx9mesh.h
@@ -152,6 +152,7 @@ extern "C" {
 
 HRESULT WINAPI D3DXCreateMesh(DWORD, DWORD, DWORD, CONST D3DVERTEXELEMENT9 *, LPDIRECT3DDEVICE9, LPD3DXMESH *);
 HRESULT WINAPI D3DXCreateBuffer(DWORD, LPD3DXBUFFER*);
+UINT    WINAPI D3DXGetDeclLength(const D3DVERTEXELEMENT9 *decl);
 UINT    WINAPI D3DXGetDeclVertexSize(const D3DVERTEXELEMENT9 *decl, DWORD stream_idx);
 UINT    WINAPI D3DXGetFVFVertexSize(DWORD);
 BOOL    WINAPI D3DXBoxBoundProbe(CONST D3DXVECTOR3 *, CONST D3DXVECTOR3 *, CONST D3DXVECTOR3 *, CONST D3DXVECTOR3 *);