diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeAMDGCN.cpp b/clang/lib/CodeGen/CGOpenMPRuntimeAMDGCN.cpp
--- a/clang/lib/CodeGen/CGOpenMPRuntimeAMDGCN.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeAMDGCN.cpp
@@ -49,13 +49,12 @@
 llvm::Value *CGOpenMPRuntimeAMDGCN::getGPUNumThreads(CodeGenFunction &CGF) {
   CGBuilderTy &Bld = CGF.Builder;
   llvm::Module *M = &CGF.CGM.getModule();
-  const char *LocSize = "__ockl_get_local_size";
+  const char *LocSize = "__kmpc_amdgcn_gpu_num_threads";
   llvm::Function *F = M->getFunction(LocSize);
   if (!F) {
     F = llvm::Function::Create(
-        llvm::FunctionType::get(CGF.Int64Ty, {CGF.Int32Ty}, false),
+        llvm::FunctionType::get(CGF.Int32Ty, llvm::None, false),
         llvm::GlobalVariable::ExternalLinkage, LocSize, &CGF.CGM.getModule());
   }
-  return Bld.CreateTrunc(
-      Bld.CreateCall(F, {Bld.getInt32(0)}, "nvptx_num_threads"), CGF.Int32Ty);
+  return Bld.CreateCall(F, llvm::None, "nvptx_num_threads");
 }
diff --git a/openmp/libomptarget/deviceRTLs/amdgcn/src/amdgcn_interface.h b/openmp/libomptarget/deviceRTLs/amdgcn/src/amdgcn_interface.h
--- a/openmp/libomptarget/deviceRTLs/amdgcn/src/amdgcn_interface.h
+++ b/openmp/libomptarget/deviceRTLs/amdgcn/src/amdgcn_interface.h
@@ -15,4 +15,6 @@
 typedef uint64_t __kmpc_impl_lanemask_t;
 typedef uint32_t omp_lock_t; /* arbitrary type of the right length */
 
+EXTERN uint32_t __kmpc_amdgcn_gpu_num_threads(void);
+
 #endif
diff --git a/openmp/libomptarget/deviceRTLs/amdgcn/src/target_impl.hip b/openmp/libomptarget/deviceRTLs/amdgcn/src/target_impl.hip
--- a/openmp/libomptarget/deviceRTLs/amdgcn/src/target_impl.hip
+++ b/openmp/libomptarget/deviceRTLs/amdgcn/src/target_impl.hip
@@ -144,6 +144,11 @@
   return __builtin_amdgcn_mbcnt_hi(~0u, __builtin_amdgcn_mbcnt_lo(~0u, 0u));
 }
 
+EXTERN uint32_t __kmpc_amdgcn_gpu_num_threads(void)
+{
+  return GetNumberOfThreadsInBlock();
+}
+
 // Stub implementations
-DEVICE void *__kmpc_impl_malloc(size_t ) { return nullptr }
+DEVICE void *__kmpc_impl_malloc(size_t ) { return nullptr; }
 DEVICE void __kmpc_impl_free(void *) {}