diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -16372,8 +16372,12 @@
   ExprResult Allocator = DefaultLvalueConversion(A);
   if (Allocator.isInvalid())
     return nullptr;
-  Allocator = PerformImplicitConversion(Allocator.get(),
-                                        DSAStack->getOMPAllocatorHandleT(),
+  QualType AllocatorHT = DSAStack->getOMPAllocatorHandleT();
+  if (!AllocatorHT->isEnumeralType() && AllocatorHT->isIntegerType())
+    // allocator_handler_t is enum type.  For int type convert to
+    // UnsignedPointerDiffType avoid truncate.
+    AllocatorHT = Context.getUnsignedPointerDiffType();
+  Allocator = PerformImplicitConversion(Allocator.get(), AllocatorHT,
                                         Sema::AA_Initializing,
                                         /*AllowExplicit=*/true);
   if (Allocator.isInvalid())
diff --git a/clang/test/OpenMP/omp_init_allocator.c b/clang/test/OpenMP/omp_init_allocator.c
new file mode 100644
--- /dev/null
+++ b/clang/test/OpenMP/omp_init_allocator.c
@@ -0,0 +1,61 @@
+// RUN: %clang_cc1 -isystem %S/Inputs -emit-llvm -o - -fopenmp \
+// RUN: -fopenmp-version=50 -triple x86_64-unknown-linux-gnu %s | FileCheck %s
+
+typedef enum {
+  omp_atk_sync_hint = 1,
+  omp_atk_alignment = 2
+} omp_alloctrait_key_t;
+typedef unsigned long int uintptr_t;
+typedef uintptr_t omp_uintptr_t;
+typedef struct {
+  omp_alloctrait_key_t key;
+  omp_uintptr_t value;
+} omp_alloctrait_t;
+typedef enum omp_allocator_handle_t {
+  omp_null_allocator = 0,
+  omp_default_mem_alloc = 1,
+  omp_large_cap_mem_alloc = 2,
+  omp_const_mem_alloc = 3,
+  omp_high_bw_mem_alloc = 4,
+  omp_low_lat_mem_alloc = 5,
+  omp_cgroup_mem_alloc = 6,
+  omp_pteam_mem_alloc = 7,
+  omp_thread_mem_alloc = 8,
+
+  omp_target_host_mem_alloc = 100,
+  omp_target_shared_mem_alloc = 101,
+  omp_target_device_mem_alloc = 102,
+  KMP_ALLOCATOR_MAX_HANDLE = (18446744073709551615UL)
+} omp_allocator_handle_t;
+typedef enum omp_memspace_handle_t {
+  omp_default_mem_space = 0,
+  omp_large_cap_mem_space = 1,
+  omp_const_mem_space = 2,
+  omp_high_bw_mem_space = 3,
+  omp_low_lat_mem_space = 4,
+
+  omp_target_host_mem_space = 100,
+  omp_target_shared_mem_space = 101,
+  omp_target_device_mem_space = 102,
+  KMP_MEMSPACE_MAX_HANDLE = (18446744073709551615UL)
+} omp_memspace_handle_t;
+
+extern omp_allocator_handle_t omp_init_allocator(omp_memspace_handle_t m,
+                                                 int ntraits,
+                                                 omp_alloctrait_t traits[]);
+//CHECK-LABEL: test_allocate_allocator
+void test_allocate_allocator() {
+  omp_alloctrait_t x_traits[1] = {{omp_atk_alignment, 64}};
+  omp_allocator_handle_t x_alloc =
+      omp_init_allocator(omp_default_mem_space, 1, x_traits);
+  {
+    int x;
+// CHECK: [[RET:%.+]] = call i64 @omp_init_allocator
+// CHECK-NEXT: store i64 [[RET]], ptr [[X_ALLOC:%x_alloc]]
+// CHECK: [[TMP:%.+]] = load i64, ptr [[X_ALLOC]]
+// CHECK-NEXT: [[CONV:%conv]] = inttoptr i64 [[TMP]] to ptr
+// CHECK-NEXT: call ptr @__kmpc_alloc(i32 %0, i64 4, ptr [[CONV]])
+// CHECK-NOT: trunc
+#pragma omp allocate(x) allocator(x_alloc)
+  }
+}
diff --git a/openmp/runtime/test/api/omp_init_allocator.c b/openmp/runtime/test/api/omp_init_allocator.c
new file mode 100644
--- /dev/null
+++ b/openmp/runtime/test/api/omp_init_allocator.c
@@ -0,0 +1,20 @@
+// RUN: %libomp-compile-and-run
+
+#include <omp.h>
+#include <stdio.h>
+
+void test_allocate_allocator() {
+  omp_alloctrait_t x_traits[1] = {{omp_atk_alignment, 64}};
+  omp_allocator_handle_t x_alloc =
+      omp_init_allocator(omp_default_mem_space, 1, x_traits);
+  {
+    int x;
+#pragma omp allocate(x) allocator(x_alloc)
+  }
+  omp_destroy_allocator(x_alloc);
+}
+
+int main() {
+  test_allocate_allocator();
+  printf("passed\n");
+}