diff --git a/libc/cmake/modules/LLVMLibCTestRules.cmake b/libc/cmake/modules/LLVMLibCTestRules.cmake
--- a/libc/cmake/modules/LLVMLibCTestRules.cmake
+++ b/libc/cmake/modules/LLVMLibCTestRules.cmake
@@ -421,7 +421,7 @@
     "INTEGRATION_TEST"
     "" # No optional arguments
     "SUITE" # Single value arguments
-    "SRCS;HDRS;DEPENDS;ARGS;ENV;COMPILE_OPTIONS" # Multi-value arguments
+    "SRCS;HDRS;DEPENDS;ARGS;ENV;COMPILE_OPTIONS;LOADER_ARGS" # Multi-value arguments
     ${ARGN}
   )
 
@@ -532,6 +532,7 @@
     ${fq_target_name}
     COMMAND ${INTEGRATION_TEST_ENV}
             $<$<BOOL:${LIBC_TARGET_ARCHITECTURE_IS_GPU}>:${gpu_loader_exe}>
+            ${INTEGRATION_TEST_LOADER_ARGS}
             $<TARGET_FILE:${fq_build_target_name}> ${INTEGRATION_TEST_ARGS}
     COMMENT "Running integration test ${fq_target_name}"
   )
diff --git a/libc/test/integration/startup/gpu/CMakeLists.txt b/libc/test/integration/startup/gpu/CMakeLists.txt
--- a/libc/test/integration/startup/gpu/CMakeLists.txt
+++ b/libc/test/integration/startup/gpu/CMakeLists.txt
@@ -20,4 +20,6 @@
     rpc_test.cpp
   DEPENDS
     libc.src.__support.RPC.rpc_client
+  LOADER_ARGS
+    --blocks 16
 )
diff --git a/libc/test/integration/startup/gpu/rpc_test.cpp b/libc/test/integration/startup/gpu/rpc_test.cpp
--- a/libc/test/integration/startup/gpu/rpc_test.cpp
+++ b/libc/test/integration/startup/gpu/rpc_test.cpp
@@ -11,10 +11,20 @@
 
 using namespace __llvm_libc;
 
+#if defined(LIBC_TARGET_ARCH_IS_NVPTX)
+uint32_t __nvvm_read_ptx_sreg_ctaid_x();
+uint32_t get_block_id() { return __nvvm_read_ptx_sreg_ctaid_x(); }
+#elif defined(LIBC_TARGET_ARCH_IS_AMDGPU)
+uint32_t __builtin_amdgcn_workitem_id_x();
+uint32_t get_block_id() { return __builtin_amdgcn_workgroup_id_x(); }
+#else
+uint32_t get_block_id() { return 0; }
+#endif
+
 static void test_add_simple() {
-  constexpr int num_additions = 10000;
+  uint32_t num_additions = 1000 + 10 * get_block_id();
   uint64_t cnt = 0;
-  for (int i = 0; i < num_additions; ++i) {
+  for (uint32_t i = 0; i < num_additions; ++i) {
     rpc::Port port = rpc::client.open(rpc::TEST_INCREMENT);
     port.send_and_recv([=](rpc::Buffer *buffer) { buffer->data[0] = cnt; },
                        [&](rpc::Buffer *buffer) { cnt = buffer->data[0]; });