diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -655,9 +655,13 @@
       InitRVal =
           RValue::getComplex(CGF.EmitLoadOfComplex(LV, DRD->getLocation()));
       break;
-    case TEK_Aggregate:
-      InitRVal = RValue::getAggregate(LV.getAddress(CGF));
-      break;
+    case TEK_Aggregate: {
+      OpaqueValueExpr OVE(DRD->getLocation(), Ty, VK_LValue);
+      CodeGenFunction::OpaqueValueMapping OpaqueMap(CGF, &OVE, LV);
+      CGF.EmitAnyExprToMem(&OVE, Private, Ty.getQualifiers(),
+                           /*IsInitializer=*/false);
+      return;
+    }
     }
     OpaqueValueExpr OVE(DRD->getLocation(), Ty, VK_RValue);
     CodeGenFunction::OpaqueValueMapping OpaqueMap(CGF, &OVE, InitRVal);
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
@@ -16567,8 +16567,7 @@
     }
     if (RHSVD->isInvalidDecl())
       continue;
-    if (!RHSVD->hasInit() &&
-        (DeclareReductionRef.isUnset() || !S.LangOpts.CPlusPlus)) {
+    if (!RHSVD->hasInit() && DeclareReductionRef.isUnset()) {
       S.Diag(ELoc, diag::err_omp_reduction_id_not_compatible)
           << Type << ReductionIdRange;
       bool IsDecl = !VD || VD->isThisDeclarationADefinition(Context) ==
diff --git a/clang/test/OpenMP/declare_reduction_ast_print.c b/clang/test/OpenMP/declare_reduction_ast_print.c
--- a/clang/test/OpenMP/declare_reduction_ast_print.c
+++ b/clang/test/OpenMP/declare_reduction_ast_print.c
@@ -47,13 +47,18 @@
                               : omp_out = omp_out > omp_in ? omp_in : omp_out) \
     initializer(omp_priv = 2147483647)
 
+#pragma omp declare reduction(mymin        \
+                              : struct SSS \
+                              : omp_out = omp_out.field > omp_in.field ? omp_in : omp_out)
+
 int foo(int argc, char **argv) {
   int x;
-#pragma omp parallel for reduction(mymin : x)
+  struct SSS ss;
+#pragma omp parallel for reduction(mymin : x, ss)
   for (int i = 0; i < 1000; i++)
     ;
   return 0;
 }
 
-// CHECK: #pragma omp parallel for reduction(mymin: x)
+// CHECK: #pragma omp parallel for reduction(mymin: x,ss)
 #endif
diff --git a/clang/test/OpenMP/declare_reduction_codegen.c b/clang/test/OpenMP/declare_reduction_codegen.c
--- a/clang/test/OpenMP/declare_reduction_codegen.c
+++ b/clang/test/OpenMP/declare_reduction_codegen.c
@@ -17,6 +17,9 @@
 // CHECK: [[SSS_INT:.+]] = type { i32 }
 // CHECK-LOAD: [[SSS_INT:.+]] = type { i32 }
 
+// CHECK-DAG: [[SSS_INIT:@.+]] = private constant %struct.SSS zeroinitializer
+// CHECK-DAG: [[INT_INIT:@.+]] = private constant i32 0
+
 #pragma omp declare reduction(+ : int, char : omp_out *= omp_in)
 // CHECK: define internal {{.*}}void @{{[^(]+}}(i32* noalias %0, i32* noalias %1)
 // CHECK: [[MUL:%.+]] = mul nsw i32
@@ -163,4 +166,27 @@
 // OMP45-LOAD-NEXT: store i8 [[TRUNC]], i8*
 // OMP45-LOAD-NEXT: ret void
 // OMP45-LOAD-NEXT: }
+
+// CHECK-LABEL: bar
+struct SSS ss;
+int in;
+void bar() {
+  // CHECK: [[SS_PRIV:%.+]] = alloca %struct.SSS,
+  // CHECK: [[IN_PRIV:%.+]] = alloca i32,
+  // CHECK: [[BC:%.+]] = bitcast %struct.SSS* [[SS_PRIV]] to i8*
+  // CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 [[BC]], i8* align 4 bitcast (%struct.SSS* [[SSS_INIT]] to i8*), i64 4, i1 false)
+  // CHECK: [[IN_VAL:%.+]] = load i32, i32* [[INT_INIT]],
+  // CHECK: store i32 [[IN_VAL]], i32* [[IN_PRIV]],
+  // CHECK: call void @__kmpc_for_static_init_4(
+#pragma omp declare reduction(+            \
+                              : struct SSS \
+                              : omp_out = omp_in)
+#pragma omp declare reduction(+     \
+                              : int \
+                              : omp_out = omp_in)
+#pragma omp for reduction(+ \
+                          : ss, in)
+  for (int i = 0; i < 10; ++i)
+    ;
+}
 #endif
diff --git a/clang/test/OpenMP/declare_reduction_messages.c b/clang/test/OpenMP/declare_reduction_messages.c
--- a/clang/test/OpenMP/declare_reduction_messages.c
+++ b/clang/test/OpenMP/declare_reduction_messages.c
@@ -49,9 +49,9 @@
 #pragma omp declare reduction(|: struct S: omp_out.s += omp_in.s) initializer(omp_priv = { 0 })
 
 int fun(int arg) {
-  struct S s;// expected-note {{'s' defined here}}
+  struct S s;
   s.s = 0;
-#pragma omp parallel for reduction(+ : s) // expected-error {{list item of type 'struct S' is not valid for specified reduction operation: unable to provide default initialization value}}
+#pragma omp parallel for reduction(+ : s)
   for (arg = 0; arg < 10; ++arg)
     s.s += arg;
 #pragma omp declare reduction(red : int : omp_out++)