diff --git a/source/opt/aggressive_dead_code_elim_pass.cpp b/source/opt/aggressive_dead_code_elim_pass.cpp
index 9d7256b..83f61c1 100644
--- a/source/opt/aggressive_dead_code_elim_pass.cpp
+++ b/source/opt/aggressive_dead_code_elim_pass.cpp
@@ -997,6 +997,7 @@
       "SPV_KHR_terminate_invocation",
       "SPV_KHR_shader_clock",
       "SPV_KHR_vulkan_memory_model",
+      "SPV_KHR_subgroup_uniform_control_flow",
   });
 }
 
diff --git a/source/opt/local_access_chain_convert_pass.cpp b/source/opt/local_access_chain_convert_pass.cpp
index 205cd7a..43770e5 100644
--- a/source/opt/local_access_chain_convert_pass.cpp
+++ b/source/opt/local_access_chain_convert_pass.cpp
@@ -418,6 +418,7 @@
       "SPV_KHR_ray_query",
       "SPV_EXT_fragment_invocation_density",
       "SPV_KHR_terminate_invocation",
+      "SPV_KHR_subgroup_uniform_control_flow",
   });
 }
 
diff --git a/source/opt/local_single_block_elim_pass.cpp b/source/opt/local_single_block_elim_pass.cpp
index 5f35ee1..50476dc 100644
--- a/source/opt/local_single_block_elim_pass.cpp
+++ b/source/opt/local_single_block_elim_pass.cpp
@@ -270,6 +270,7 @@
       "SPV_EXT_fragment_invocation_density",
       "SPV_EXT_physical_storage_buffer",
       "SPV_KHR_terminate_invocation",
+      "SPV_KHR_subgroup_uniform_control_flow",
   });
 }
 
diff --git a/source/opt/local_single_store_elim_pass.cpp b/source/opt/local_single_store_elim_pass.cpp
index d322a2f..286888e 100644
--- a/source/opt/local_single_store_elim_pass.cpp
+++ b/source/opt/local_single_store_elim_pass.cpp
@@ -123,6 +123,7 @@
       "SPV_EXT_fragment_invocation_density",
       "SPV_EXT_physical_storage_buffer",
       "SPV_KHR_terminate_invocation",
+      "SPV_KHR_subgroup_uniform_control_flow",
   });
 }
 bool LocalSingleStoreElimPass::ProcessVariable(Instruction* var_inst) {
diff --git a/test/text_to_binary.extension_test.cpp b/test/text_to_binary.extension_test.cpp
index 8c42f72..8bfdf28 100644
--- a/test/text_to_binary.extension_test.cpp
+++ b/test/text_to_binary.extension_test.cpp
@@ -935,6 +935,22 @@
                                  MakeVector("SPV_KHR_expect_assume"))},
                 {"OpAssumeTrueKHR %1\n",
                  MakeInstruction(SpvOpAssumeTrueKHR, {1})}})));
+// SPV_KHR_subgroup_uniform_control_flow
+
+INSTANTIATE_TEST_SUITE_P(
+    SPV_KHR_subgroup_uniform_control_flow, ExtensionRoundTripTest,
+    Combine(Values(SPV_ENV_UNIVERSAL_1_0, SPV_ENV_UNIVERSAL_1_3,
+                   SPV_ENV_VULKAN_1_0, SPV_ENV_VULKAN_1_1, SPV_ENV_VULKAN_1_2),
+            ValuesIn(std::vector<AssemblyCase>{
+                {"OpExtension \"SPV_KHR_subgroup_uniform_control_flow\"\n",
+                 MakeInstruction(
+                     SpvOpExtension,
+                     MakeVector("SPV_KHR_subgroup_uniform_control_flow"))},
+                {"OpExecutionMode %1 SubgroupUniformControlFlowKHR\n",
+                 MakeInstruction(
+                     SpvOpExecutionMode,
+                     {1, SpvExecutionModeSubgroupUniformControlFlowKHR})},
+            })));
 
 }  // namespace
 }  // namespace spvtools
diff --git a/test/text_to_binary.mode_setting_test.cpp b/test/text_to_binary.mode_setting_test.cpp
index 8ddf421..647bb3d 100644
--- a/test/text_to_binary.mode_setting_test.cpp
+++ b/test/text_to_binary.mode_setting_test.cpp
@@ -189,6 +189,7 @@
                 {CASE(OutputTriangleStrip), {}},
                 {CASE(VecTypeHint), {96}},
                 {CASE(ContractionOff), {}},
+                {CASE(SubgroupUniformControlFlowKHR), {}},
             })));
 
 INSTANTIATE_TEST_SUITE_P(
diff --git a/test/val/CMakeLists.txt b/test/val/CMakeLists.txt
index 4aec249..7792b4f 100644
--- a/test/val/CMakeLists.txt
+++ b/test/val/CMakeLists.txt
@@ -40,6 +40,7 @@
        val_extensions_test.cpp
        val_extension_spv_khr_expect_assume.cpp
        val_extension_spv_khr_linkonce_odr.cpp
+       val_extension_spv_khr_subgroup_uniform_control_flow.cpp
        val_extension_spv_khr_terminate_invocation.cpp
        val_ext_inst_test.cpp
        ${VAL_TEST_COMMON_SRCS}
diff --git a/test/val/val_extension_spv_khr_subgroup_uniform_control_flow.cpp b/test/val/val_extension_spv_khr_subgroup_uniform_control_flow.cpp
new file mode 100644
index 0000000..f528cb9
--- /dev/null
+++ b/test/val/val_extension_spv_khr_subgroup_uniform_control_flow.cpp
@@ -0,0 +1,110 @@
+// Copyright (c) 2021 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Tests for OpExtension validator rules.
+
+#include <string>
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "source/enum_string_mapping.h"
+#include "source/extensions.h"
+#include "source/spirv_target_env.h"
+#include "test/test_fixture.h"
+#include "test/unit_spirv.h"
+#include "test/val/val_fixtures.h"
+
+namespace spvtools {
+namespace val {
+namespace {
+
+using ::testing::HasSubstr;
+using ::testing::Values;
+using ::testing::ValuesIn;
+
+using ValidateSpvKHRSubgroupUniformControlFlow = spvtest::ValidateBase<bool>;
+
+TEST_F(ValidateSpvKHRSubgroupUniformControlFlow, Valid) {
+  const std::string str = R"(
+    OpCapability Shader
+    OpExtension "SPV_KHR_subgroup_uniform_control_flow"
+    OpMemoryModel Logical Simple
+    OpEntryPoint GLCompute %main "main"
+    OpExecutionMode %main LocalSize 1 1 1
+    OpExecutionMode %main SubgroupUniformControlFlowKHR
+    
+    %void    = OpTypeVoid
+    %void_fn = OpTypeFunction %void
+
+    %main = OpFunction %void None %void_fn
+    %entry = OpLabel
+    OpReturn
+    OpFunctionEnd
+)";
+  CompileSuccessfully(str.c_str());
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
+}
+
+TEST_F(ValidateSpvKHRSubgroupUniformControlFlow, RequiresExtension) {
+  const std::string str = R"(
+    OpCapability Shader
+    OpMemoryModel Logical Simple
+    OpEntryPoint GLCompute %main "main"
+    OpExecutionMode %main LocalSize 1 1 1
+    OpExecutionMode %main SubgroupUniformControlFlowKHR
+    
+    %void    = OpTypeVoid
+    %void_fn = OpTypeFunction %void
+
+    %main = OpFunction %void None %void_fn
+    %entry = OpLabel
+    OpReturn
+    OpFunctionEnd
+)";
+  CompileSuccessfully(str.c_str());
+  EXPECT_NE(SPV_SUCCESS, ValidateInstructions());
+  EXPECT_THAT(getDiagnosticString(),
+              HasSubstr("2nd operand of ExecutionMode: operand "
+                        "SubgroupUniformControlFlowKHR(4421) "
+                        "requires one of these extensions: "
+                        "SPV_KHR_subgroup_uniform_control_flow"));
+}
+
+TEST_F(ValidateSpvKHRSubgroupUniformControlFlow, RequiresShaderCapability) {
+  const std::string str = R"(
+    OpCapability Kernel
+    OpCapability Addresses
+    OpExtension "SPV_KHR_subgroup_uniform_control_flow"
+    OpMemoryModel Physical32 OpenCL
+    OpEntryPoint Kernel %main "main"
+    OpExecutionMode %main SubgroupUniformControlFlowKHR
+    
+    %void    = OpTypeVoid
+    %void_fn = OpTypeFunction %void
+
+    %main = OpFunction %void None %void_fn
+    %entry = OpLabel
+    OpReturn
+    OpFunctionEnd
+)";
+  CompileSuccessfully(str.c_str());
+  EXPECT_NE(SPV_SUCCESS, ValidateInstructions());
+  EXPECT_THAT(getDiagnosticString(),
+              HasSubstr("Operand 2 of ExecutionMode requires one of these "
+                        "capabilities: Shader"));
+}
+
+}  // namespace
+}  // namespace val
+}  // namespace spvtools