diff --git a/sycl/test/esimd/vec_arg_call_conv_ext.cpp b/sycl/test/esimd/vec_arg_call_conv_ext.cpp
new file mode 100644
index 0000000000000..a4cdc137b7192
--- /dev/null
+++ b/sycl/test/esimd/vec_arg_call_conv_ext.cpp
@@ -0,0 +1,71 @@
+// RUN: %clangxx -fsycl -Xclang -opaque-pointers -fsycl-device-only -Xclang -emit-llvm -o %t.comp.ll %s
+// RUN: sycl-post-link -ir-output-only -lower-esimd -S %t.comp.ll -o %t.out.ll
+// RUN: FileCheck --input-file=%t.out.ll %s
+
+// Checks that ESIMDOptimizeVecArgCallConv does the right job as
+// a part of sycl-post-link.
+
+#include <sycl/ext/intel/esimd.hpp>
+
+using namespace sycl::ext::intel::esimd;
+
+// clang-format off
+
+//------------------------
+// Test1: Optimized parameter interleaves non - optimizeable ones.
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<int, 8> callee__sret__x_param_x(int i, simd<int, 8> x, int j) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func <8 x i32> @_Z23callee__sret__x_param_x{{.*}}(i32 noundef %{{.*}}, <8 x i32> %{{.*}}, i32 noundef %{{.*}})
+  return x + (i + j);
+}
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<int, 8> test__sret__x_param_x(simd<int, 8> x) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func <8 x i32> @_Z21test__sret__x_param_x{{.*}}(<8 x i32> %{{.*}})
+  return callee__sret__x_param_x(2, x, 1);
+// CHECK:  %{{.*}} = call spir_func <8 x i32> @_Z23callee__sret__x_param_x{{.*}}(i32 2, <8 x i32> %{{.*}}, i32 1)
+}
+
+//------------------------
+// Test2: "2-level fall through"
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<double, 32> callee__all_fall_through0(simd<double, 32> x) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func <32 x double> @_Z25callee__all_fall_through0{{.*}}(<32 x double> %{{.*}})
+  return x;
+}
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<double, 32> callee__all_fall_through1(simd<double, 32> x) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func <32 x double> @_Z25callee__all_fall_through1{{.*}}(<32 x double> %{{.*}})
+  return callee__all_fall_through0(x);
+// CHECK:  %{{.*}} = call spir_func <32 x double> @_Z25callee__all_fall_through0{{.*}}(<32 x double> %{{.*}})
+}
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<double, 32> test__all_fall_through(simd<double, 32> x) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func <32 x double> @_Z22test__all_fall_through{{.*}}(<32 x double> %{{.*}})
+  return callee__all_fall_through1(x);
+// CHECK:  %{{.*}} = call spir_func <32 x double> @_Z25callee__all_fall_through1{{.*}}(<32 x double> %{{.*}})
+}
+
+//------------------------
+// Test3. First argument is passed by reference and updated in the callee,
+// must not be optimized.
+
+__attribute__((noinline))
+SYCL_EXTERNAL void callee_void__noopt_opt(simd<int, 8>& x, simd<int, 8> y) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func void @_Z22callee_void__noopt_opt{{.*}}(ptr {{.*}} %{{.*}}, <8 x i32> %{{.*}})
+  x = x + y;
+}
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<int, 8> test__sret__noopt_opt(simd<int, 8> x) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func <8 x i32> @_Z21test__sret__noopt_opt{{.*}}(ptr noundef %{{.*}})
+  callee_void__noopt_opt(x, x);
+// CHECK:  call spir_func void @_Z22callee_void__noopt_opt{{.*}}(ptr addrspace(4) %{{.*}}, <8 x i32> %{{.*}})
+  return x;
+}
+
+//------------------------
diff --git a/sycl/test/esimd/vec_arg_call_conv_smoke.cpp b/sycl/test/esimd/vec_arg_call_conv_smoke.cpp
new file mode 100644
index 0000000000000..8f1f184842a4b
--- /dev/null
+++ b/sycl/test/esimd/vec_arg_call_conv_smoke.cpp
@@ -0,0 +1,40 @@
+// RUN: %clangxx -fsycl -Xclang -opaque-pointers -fsycl-device-only -Xclang -emit-llvm -o %t.comp.ll %s
+// RUN: sycl-post-link -ir-output-only -lower-esimd -S %t.comp.ll -o %t.out.ll
+// RUN: FileCheck --input-file=%t.out.ll %s
+
+// Performs a basic check that ESIMDOptimizeVecArgCallConv does the right job as
+// a part of sycl-post-link.
+
+#include <sycl/ext/intel/esimd.hpp>
+
+using namespace sycl::ext::intel::esimd;
+
+ESIMD_PRIVATE simd<float, 3 * 32 * 4> GRF;
+#define V(x, w, i) (x).template select<w, 1>(i)
+
+// clang-format off
+
+// "Fall-through case", incoming optimizeable parameter is just returned
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<float, 16> callee__sret__param(simd<float, 16> x) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func <16 x float> @_Z19callee__sret__param{{.*}}(<16 x float> %[[PARAM:.+]])
+  return x;
+}
+
+// * Caller 1: simd object is read from array
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<float, 16> test__sret__fall_through__arr(simd<float, 16> *x, int i) SYCL_ESIMD_FUNCTION {
+// CHECK: define dso_local spir_func <16 x float> @_Z29test__sret__fall_through__arr{{.*}}(ptr addrspace(4) noundef %[[PARAM0:.+]], i32 noundef %{{.*}})
+  return callee__sret__param(x[i]);
+// CHECK: %{{.*}} = call spir_func <16 x float> @_Z19callee__sret__param{{.*}}(<16 x float> %{{.*}})
+}
+
+// * Caller 2 : simd object is read from a global
+
+__attribute__((noinline))
+SYCL_EXTERNAL simd<float, 16> test__sret__fall_through__glob() SYCL_ESIMD_FUNCTION {
+  return callee__sret__param(V(GRF, 16, 0));
+// CHECK: %{{.*}} = call spir_func <16 x float> @_Z19callee__sret__param{{.*}}(<16 x float> %{{.*}})
+}