diff --git a/clang/lib/Headers/opencl-c-base.h b/clang/lib/Headers/opencl-c-base.h
--- a/clang/lib/Headers/opencl-c-base.h
+++ b/clang/lib/Headers/opencl-c-base.h
@@ -39,6 +39,14 @@
 #define __opencl_c_images 1
 #endif
 
+// Define header-only feature macros for OpenCL C 3.0.
+#if (__OPENCL_C_VERSION__ == 300)
+// For the SPIR target all features are supported.
+#if defined(__SPIR__)
+#define __opencl_c_atomic_scope_all_devices 1
+#endif // defined(__SPIR__)
+#endif // (__OPENCL_C_VERSION__ == 300)
+
 // built-in scalar data types:
 
 /**
@@ -312,7 +320,12 @@
   memory_scope_work_item = __OPENCL_MEMORY_SCOPE_WORK_ITEM,
   memory_scope_work_group = __OPENCL_MEMORY_SCOPE_WORK_GROUP,
   memory_scope_device = __OPENCL_MEMORY_SCOPE_DEVICE,
+#if defined(__opencl_c_atomic_scope_all_devices)
   memory_scope_all_svm_devices = __OPENCL_MEMORY_SCOPE_ALL_SVM_DEVICES,
+#if (__OPENCL_C_VERSION__ >= CL_VERSION_3_0)
+  memory_scope_all_devices = memory_scope_all_svm_devices,
+#endif // __OPENCL_C_VERSION__ >= CL_VERSION_3_0
+#endif // defined(__opencl_c_atomic_scope_all_devices)
 #if defined(cl_intel_subgroups) || defined(cl_khr_subgroups)
   memory_scope_sub_group = __OPENCL_MEMORY_SCOPE_SUB_GROUP
 #endif
diff --git a/clang/test/Headers/opencl-c-header.cl b/clang/test/Headers/opencl-c-header.cl
--- a/clang/test/Headers/opencl-c-header.cl
+++ b/clang/test/Headers/opencl-c-header.cl
@@ -151,7 +151,13 @@
 #endif //(defined(__OPENCL_CPP_VERSION__) || __OPENCL_C_VERSION__ >= 200)
 
 // OpenCL C features.
-#if (defined(__OPENCL_CPP_VERSION__) || __OPENCL_C_VERSION__ == 200)
+#if (__OPENCL_C_VERSION__ == 300)
+
+#if __opencl_c_atomic_scope_all_devices != 1
+#error "Incorrectly defined feature macro __opencl_c_atomic_scope_all_devices"
+#endif
+
+#elif (defined(__OPENCL_CPP_VERSION__) || __OPENCL_C_VERSION__ == 200)
 
 #ifndef  __opencl_c_pipes
 #error "Feature macro __opencl_c_pipes should be defined"
diff --git a/clang/test/SemaOpenCL/atomic-ops.cl b/clang/test/SemaOpenCL/atomic-ops.cl
--- a/clang/test/SemaOpenCL/atomic-ops.cl
+++ b/clang/test/SemaOpenCL/atomic-ops.cl
@@ -2,6 +2,7 @@
 // RUN:   -fsyntax-only -triple=spir64 -fdeclare-opencl-builtins -finclude-default-header
 // RUN: %clang_cc1 %s -cl-std=CL2.0 -verify -fsyntax-only \
 // RUN:   -triple=amdgcn-amd-amdhsa -fdeclare-opencl-builtins -finclude-default-header
+// TODO: add -cl-std=CL3.0 line when generic and psv are supported.
 
 // Basic parsing/Sema tests for __opencl_atomic_*
 
@@ -161,6 +162,11 @@
   (void)__opencl_atomic_load(Ap, memory_order_relaxed, memory_scope_work_group);
   (void)__opencl_atomic_load(Ap, memory_order_relaxed, memory_scope_device);
   (void)__opencl_atomic_load(Ap, memory_order_relaxed, memory_scope_all_svm_devices);
+  (void)__opencl_atomic_load(Ap, memory_order_relaxed, memory_scope_all_devices);
+#if __OPENCL_C_VERSION__ < CL_VERSION_3_0
+  // expected-error@-2{{use of undeclared identifier 'memory_scope_all_devices'}}
+  // expected-note@* {{'memory_scope_all_svm_devices' declared here}}
+#endif
   (void)__opencl_atomic_load(Ap, memory_order_relaxed, memory_scope_sub_group);
   (void)__opencl_atomic_load(Ap, memory_order_relaxed, scope);
   (void)__opencl_atomic_load(Ap, memory_order_relaxed, 10);    //expected-error{{synchronization scope argument to atomic operation is invalid}}