diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -202,7 +202,6 @@
 /// float-to-int conversion instructions.
 CODEGENOPT(StrictFloatCastOverflow, 1, 1)
 
-CODEGENOPT(UniformWGSize     , 1, 0) ///< -cl-uniform-work-group-size
 CODEGENOPT(NoZeroInitializedInBSS , 1, 0) ///< -fno-zero-initialized-in-bss.
 /// Method of Objective-C dispatch to use.
 ENUM_CODEGENOPT(ObjCDispatchMethod, ObjCDispatchMethodKind, 2, Legacy)
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -278,6 +278,7 @@
 ENUM_LANGOPT(SYCLVersion  , SYCLMajorVersion, 2, SYCL_None, "Version of the SYCL standard used")
 
 LANGOPT(HIPUseNewLaunchAPI, 1, 0, "Use new kernel launching API for HIP")
+LANGOPT(OffloadUniformBlock, 1, 0, "Assume that kernels are launched with uniform block sizes (default true for CUDA/HIP and false otherwise)")
 
 LANGOPT(SizedDeallocation , 1, 0, "sized deallocation")
 LANGOPT(AlignedAllocation , 1, 0, "aligned allocation")
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -912,6 +912,12 @@
 def b : JoinedOrSeparate<["-"], "b">, Flags<[LinkerInput]>,
   HelpText<"Pass -b <arg> to the linker on AIX">, MetaVarName<"<arg>">,
   Group<Link_Group>;
+
+defm offload_uniform_block : BoolFOption<"offload-uniform-block",
+  LangOpts<"OffloadUniformBlock">, Default<"LangOpts->CUDA">,
+  PosFlag<SetTrue, [CC1Option], "Assume">, NegFlag<SetFalse, [CC1Option], "Don't assume">,
+  BothFlags<[], " that kernels are launched with uniform block sizes (default true for CUDA/HIP and false otherwise)">>;
+
 // OpenCL-only Options
 def cl_opt_disable : Flag<["-"], "cl-opt-disable">, Group<opencl_Group>, Flags<[CC1Option]>,
   HelpText<"OpenCL only. This option disables all optimizations. By default optimizations are enabled.">;
@@ -947,9 +953,8 @@
 def cl_fp32_correctly_rounded_divide_sqrt : Flag<["-"], "cl-fp32-correctly-rounded-divide-sqrt">, Group<opencl_Group>, Flags<[CC1Option]>,
   HelpText<"OpenCL only. Specify that single precision floating-point divide and sqrt used in the program source are correctly rounded.">,
   MarshallingInfoFlag<CodeGenOpts<"OpenCLCorrectlyRoundedDivSqrt">>;
-def cl_uniform_work_group_size : Flag<["-"], "cl-uniform-work-group-size">, Group<opencl_Group>, Flags<[CC1Option]>,
-  HelpText<"OpenCL only. Defines that the global work-size be a multiple of the work-group size specified to clEnqueueNDRangeKernel">,
-  MarshallingInfoFlag<CodeGenOpts<"UniformWGSize">>;
+def cl_uniform_work_group_size : Flag<["-"], "cl-uniform-work-group-size">, Group<opencl_Group>, Flags<[CC1Option]>, Alias<foffload_uniform_block>,
+  HelpText<"OpenCL only. Defines that the global work-size be a multiple of the work-group size specified to clEnqueueNDRangeKernel">;
 def cl_no_stdinc : Flag<["-"], "cl-no-stdinc">, Group<opencl_Group>,
   HelpText<"OpenCL only. Disables all standard includes containing non-native compiler types and functions.">;
 def cl_ext_EQ : CommaJoined<["-"], "cl-ext=">, Group<opencl_Group>, Flags<[CC1Option]>,
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -2397,10 +2397,15 @@
         // to the compiler that the global work-size be a multiple of
         // the work-group size specified to clEnqueueNDRangeKernel
         // (i.e. work groups are uniform).
-        FuncAttrs.addAttribute("uniform-work-group-size",
-                               llvm::toStringRef(CodeGenOpts.UniformWGSize));
+        FuncAttrs.addAttribute(
+            "uniform-work-group-size",
+            llvm::toStringRef(getLangOpts().OffloadUniformBlock));
       }
     }
+
+    if (TargetDecl->hasAttr<CUDAGlobalAttr>() &&
+        getLangOpts().OffloadUniformBlock)
+      FuncAttrs.addAttribute("uniform-work-group-size", "true");
   }
 
   // Attach "no-builtins" attributes to:
diff --git a/clang/lib/CodeGen/Targets/AMDGPU.cpp b/clang/lib/CodeGen/Targets/AMDGPU.cpp
--- a/clang/lib/CodeGen/Targets/AMDGPU.cpp
+++ b/clang/lib/CodeGen/Targets/AMDGPU.cpp
@@ -366,13 +366,6 @@
   if (FD)
     setFunctionDeclAttributes(FD, F, M);
 
-  const bool IsHIPKernel =
-      M.getLangOpts().HIP && FD && FD->hasAttr<CUDAGlobalAttr>();
-
-  // TODO: This should be moved to language specific attributes instead.
-  if (IsHIPKernel)
-    F->addFnAttr("uniform-work-group-size", "true");
-
   if (M.getContext().getTargetInfo().allowAMDGPUUnsafeFPAtomics())
     F->addFnAttr("amdgpu-unsafe-fp-atomics", "true");
 
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7280,6 +7280,9 @@
     Args.AddLastArg(CmdArgs, options::OPT_fgpu_default_stream_EQ);
   }
 
+  Args.AddLastArg(CmdArgs, options::OPT_foffload_uniform_block,
+                  options::OPT_fno_offload_uniform_block);
+
   if (IsCudaDevice || IsHIPDevice) {
     StringRef InlineThresh =
         Args.getLastArgValue(options::OPT_fgpu_inline_threshold_EQ);
diff --git a/clang/test/CodeGenCUDA/amdgpu-kernel-attrs.cu b/clang/test/CodeGenCUDA/amdgpu-kernel-attrs.cu
--- a/clang/test/CodeGenCUDA/amdgpu-kernel-attrs.cu
+++ b/clang/test/CodeGenCUDA/amdgpu-kernel-attrs.cu
@@ -10,10 +10,18 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm \
 // RUN:     -verify -o - -x hip %s | FileCheck -check-prefix=NAMD %s
 
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -foffload-uniform-block \
+// RUN:     -fcuda-is-device -emit-llvm -o - -x hip %s \
+// RUN:     | FileCheck -check-prefixes=CHECK,DEFAULT %s
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -fno-offload-uniform-block \
+// RUN:     -fcuda-is-device -emit-llvm -o - -x hip %s \
+// RUN:     | FileCheck -check-prefixes=NOUB %s
+
 #include "Inputs/cuda.h"
 
 __global__ void flat_work_group_size_default() {
 // CHECK: define{{.*}} amdgpu_kernel void @_Z28flat_work_group_size_defaultv() [[FLAT_WORK_GROUP_SIZE_DEFAULT:#[0-9]+]]
+// NOUB: define{{.*}} void @_Z28flat_work_group_size_defaultv() [[NOUB:#[0-9]+]]
 }
 
 __attribute__((amdgpu_flat_work_group_size(32, 64))) // expected-no-diagnostics
@@ -45,3 +53,5 @@
 // CHECK-DAG: attributes [[WAVES_PER_EU_2]] = {{.*}}"amdgpu-waves-per-eu"="2"
 // CHECK-DAG: attributes [[NUM_SGPR_32]] = {{.*}}"amdgpu-num-sgpr"="32"
 // CHECK-DAG: attributes [[NUM_VGPR_64]] = {{.*}}"amdgpu-num-vgpr"="64"
+
+// NOUB-NOT: "uniform-work-group-size"="true"
diff --git a/clang/test/CodeGenOpenCL/cl-uniform-wg-size.cl b/clang/test/CodeGenOpenCL/cl-uniform-wg-size.cl
--- a/clang/test/CodeGenOpenCL/cl-uniform-wg-size.cl
+++ b/clang/test/CodeGenOpenCL/cl-uniform-wg-size.cl
@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -emit-llvm -O0 -cl-std=CL1.2 -o - %s 2>&1 | FileCheck %s -check-prefixes CHECK,CHECK-UNIFORM
 // RUN: %clang_cc1 -emit-llvm -O0 -cl-std=CL2.0 -o - %s 2>&1 | FileCheck %s -check-prefixes CHECK,CHECK-NONUNIFORM
 // RUN: %clang_cc1 -emit-llvm -O0 -cl-std=CL2.0 -cl-uniform-work-group-size -o - %s 2>&1 | FileCheck %s -check-prefixes CHECK,CHECK-UNIFORM
+// RUN: %clang_cc1 -emit-llvm -O0 -cl-std=CL2.0 -foffload-uniform-block -o - %s 2>&1 | FileCheck %s -check-prefixes CHECK,CHECK-UNIFORM
 
 kernel void ker() {};
 // CHECK: define{{.*}}@ker() #0
diff --git a/clang/test/Driver/hip-options.hip b/clang/test/Driver/hip-options.hip
--- a/clang/test/Driver/hip-options.hip
+++ b/clang/test/Driver/hip-options.hip
@@ -205,3 +205,27 @@
 
 // RUN: %clang -fdriver-only -Werror --target=x86_64-unknown-linux-gnu -nostdinc -nostdlib -fgpu-approx-transcendentals \
 // RUN:   -x c++ %s 2>&1 | count 0
+/ Check -fno-offload-uniform-block is passed to clang -cc1 but
+// (default) -fno-offload-uniform-block is not.
+
+// RUN: %clang -### --target=x86_64-unknown-linux-gnu -nogpuinc -nogpulib -fno-offload-uniform-block \
+// RUN:   --cuda-gpu-arch=gfx906 %s 2>&1 | FileCheck -check-prefix=NOUNIBLK %s
+
+// NOUNIBLK: "-cc1"{{.*}} "-triple" "amdgcn-amd-amdhsa" {{.*}} "-fno-offload-uniform-block"
+// NOUNIBLK: "-cc1"{{.*}} "-triple" "x86_64-unknown-linux-gnu" {{.*}} "-fno-offload-uniform-block"
+
+// RUN: %clang -### -nogpuinc -nogpulib -foffload-uniform-block \
+// RUN:   --cuda-gpu-arch=gfx906 %s 2>&1 | FileCheck -check-prefix=UNIBLK %s
+
+// UNIBLK: "-cc1"{{.*}} "-triple" "amdgcn-amd-amdhsa" {{.*}} "-foffload-uniform-block"
+// UNIBLK: "-cc1"{{.*}} "-triple" "x86_64-unknown-linux-gnu" {{.*}} "-foffload-uniform-block"
+
+// RUN: %clang -### -nogpuinc -nogpulib \
+// RUN:   --cuda-gpu-arch=gfx906 %s 2>&1 | FileCheck -check-prefix=DEFUNIBLK %s
+
+// DEFUNIBLK-NOT: "-f{{(no-)?}}offload-uniform-block"
+
+// Check no warnings for -f[no-]offload-uniform-block.
+
+// RUN: %clang -fdriver-only -Werror --target=x86_64-unknown-linux-gnu -nogpuinc -nogpulib -fno-offload-uniform-block \
+// RUN:   -foffload-uniform-block --cuda-gpu-arch=gfx906 %s 2>&1 | count 0
diff --git a/clang/test/Driver/opencl.cl b/clang/test/Driver/opencl.cl
--- a/clang/test/Driver/opencl.cl
+++ b/clang/test/Driver/opencl.cl
@@ -17,6 +17,8 @@
 // RUN: %clang -S -### -cl-denorms-are-zero %s 2>&1 | FileCheck --check-prefix=CHECK-DENORMS-ARE-ZERO %s
 // RUN: %clang -S -### -cl-fp32-correctly-rounded-divide-sqrt %s 2>&1 | FileCheck --check-prefix=CHECK-ROUND-DIV %s
 // RUN: %clang -S -### -cl-uniform-work-group-size %s 2>&1 | FileCheck --check-prefix=CHECK-UNIFORM-WG %s
+// RUN: %clang -S -### -foffload-uniform-block %s 2>&1 | FileCheck --check-prefix=CHECK-UNIFORM-WG %s
+// RUN: %clang -S -### -fno-offload-uniform-block -cl-uniform-work-group-size %s 2>&1 | FileCheck --check-prefix=CHECK-UNIFORM-WG %s
 // RUN: not %clang -cl-std=c99 -DOPENCL %s 2>&1 | FileCheck --check-prefix=CHECK-C99 %s
 // RUN: not %clang -cl-std=invalid -DOPENCL %s 2>&1 | FileCheck --check-prefix=CHECK-INVALID %s
 // RUN: %clang -S -### -target spir-unknown-unknown %s 2>&1 | FileCheck --check-prefix=CHECK-W-SPIR-COMPAT %s
@@ -44,7 +46,7 @@
 // CHECK-DENORMS-ARE-ZERO-NOT: "-cl-denorms-are-zero"
 
 // CHECK-ROUND-DIV: "-cc1" {{.*}} "-cl-fp32-correctly-rounded-divide-sqrt"
-// CHECK-UNIFORM-WG: "-cc1" {{.*}} "-cl-uniform-work-group-size"
+// CHECK-UNIFORM-WG: "-cc1" {{.*}} "-foffload-uniform-block"
 // CHECK-C99: error: invalid value 'c99' in '-cl-std=c99'
 // CHECK-INVALID: error: invalid value 'invalid' in '-cl-std=invalid'