Index: clang/include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -82,6 +82,8 @@
   "by colon, e.g. 'gfx908:sram-ecc+:xnack-')">;
 def err_drv_bad_offload_arch_combo : Error<"Invalid offload arch combinations: %0 and %1 (For a specific "
   "processor, a feature should either exist in all offload archs, or not exist in any offload archs)">;
+def warn_drv_no_offload_arch : Warning<"no offload arch is specified. Assuming %0. Use --offload-arch=<arch> to"
+  " specify offload arch">, InGroup<HIPOptionMising>;
 def err_drv_invalid_thread_model_for_target : Error<
   "invalid thread model '%0' in '%1' for this target">;
 def err_drv_invalid_linker_name : Error<
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -1174,6 +1174,9 @@
 // ignored by CUDA.
 def HIPOnly : DiagGroup<"hip-only">;
 
+// A warning group for warnings about missing HIP options.
+def HIPOptionMising : DiagGroup<"hip-option-missing">;
+
 // Warnings which cause linking of the runtime libraries like
 // libc and the CRT to be skipped.
 def AVRRtlibLinkingQuirks : DiagGroup<"avr-rtlib-linking-quirks">;
Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -2646,8 +2646,12 @@
       // Default to sm_20 which is the lowest common denominator for
       // supported GPUs.  sm_20 code should work correctly, if
       // suboptimally, on all newer GPUs.
-      if (GpuArchList.empty())
+      if (GpuArchList.empty()) {
         GpuArchList.push_back(DefaultCudaArch);
+        if (AssociatedOffloadKind == Action::OFK_HIP)
+          C.getDriver().Diag(clang::diag::warn_drv_no_offload_arch)
+              << CudaArchToString(DefaultCudaArch);
+      }
 
       return Error;
     }
Index: clang/test/Driver/hip-no-offload-arch.hip
===================================================================
--- /dev/null
+++ clang/test/Driver/hip-no-offload-arch.hip
@@ -0,0 +1,9 @@
+// REQUIRES: clang-driver, x86-registered-target, amdgpu-registered-target, nvptx-registered-target
+
+// RUN: %clang -### -target x86_64-linux-gnu -nogpuinc -nogpulib \
+// RUN:   %s 2>&1 | FileCheck -check-prefix=WARN %s
+// WARN: warning: no offload arch is specified. Assuming gfx803. Use --offload-arch=<arch> to specify offload arch [-Whip-option-missing]
+
+// RUN: %clang -### -target x86_64-linux-gnu -nogpuinc -nogpulib \
+// RUN:   -x cuda %s 2>&1 | FileCheck -check-prefix=NOWARN %s
+// NOWARN-NOT: warning