diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -12476,6 +12476,17 @@
     }
 
     if (!Var->isInvalidDecl() && RealDecl->hasAttr<LoaderUninitializedAttr>()) {
+      if (Var->getStorageClass() == SC_Extern) {
+        Diag(Var->getLocation(), diag::err_loader_uninitialized_extern_decl)
+            << Var;
+        Var->setInvalidDecl();
+        return;
+      }
+      if (RequireCompleteType(Var->getLocation(), Var->getType(),
+                              diag::err_typecheck_decl_incomplete_type)) {
+        Var->setInvalidDecl();
+        return;
+      }
       if (CXXRecordDecl *RD = Var->getType()->getAsCXXRecordDecl()) {
         if (!RD->hasTrivialDefaultConstructor()) {
           Diag(Var->getLocation(), diag::err_loader_uninitialized_trivial_ctor);
@@ -12483,12 +12494,6 @@
           return;
         }
       }
-      if (Var->getStorageClass() == SC_Extern) {
-        Diag(Var->getLocation(), diag::err_loader_uninitialized_extern_decl)
-            << Var;
-        Var->setInvalidDecl();
-        return;
-      }
     }
 
     VarDecl::DefinitionKind DefKind = Var->isThisDeclarationADefinition();
diff --git a/clang/test/CodeGenCXX/attr-loader-uninitialized.cpp b/clang/test/CodeGenCXX/attr-loader-uninitialized.cpp
--- a/clang/test/CodeGenCXX/attr-loader-uninitialized.cpp
+++ b/clang/test/CodeGenCXX/attr-loader-uninitialized.cpp
@@ -28,3 +28,15 @@
 // Defining as arr2[] [[clang..]] raises the error: attribute cannot be applied to types
 // CHECK: @arr2 = global [4 x double] undef
 double arr2 [[clang::loader_uninitialized]] [4];
+
+template<typename T> struct templ{T * t;};
+
+// CHECK: @templ_int = global %struct.templ undef, align 8
+templ<int> templ_int [[clang::loader_uninitialized]];
+
+// CHECK: @templ_trivial = global %struct.templ.0 undef, align 8
+templ<trivial> templ_trivial [[clang::loader_uninitialized]];
+
+// CHECK: @templ_incomplete = global %struct.templ.1 undef, align 8
+struct incomplete;
+templ<incomplete> templ_incomplete [[clang::loader_uninitialized]];
diff --git a/clang/test/Sema/attr-loader-uninitialized.c b/clang/test/Sema/attr-loader-uninitialized.c
--- a/clang/test/Sema/attr-loader-uninitialized.c
+++ b/clang/test/Sema/attr-loader-uninitialized.c
@@ -10,6 +10,10 @@
 extern int external_rejected __attribute__((loader_uninitialized));
 // expected-error@-1 {{variable 'external_rejected' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
 
+struct S;
+extern struct S incomplete_external_rejected __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable 'incomplete_external_rejected' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
+
 int noargs __attribute__((loader_uninitialized(0)));
 // expected-error@-1 {{'loader_uninitialized' attribute takes no arguments}}
 
@@ -35,3 +39,8 @@
 
 extern __attribute__((visibility("hidden"))) int extern_hidden __attribute__((loader_uninitialized));
 // expected-error@-1 {{variable 'extern_hidden' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
+
+struct Incomplete;
+struct Incomplete incomplete __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable has incomplete type 'struct Incomplete'}}
+// expected-note@-3 {{forward declaration of 'struct Incomplete'}}
diff --git a/clang/test/Sema/attr-loader-uninitialized.cpp b/clang/test/Sema/attr-loader-uninitialized.cpp
--- a/clang/test/Sema/attr-loader-uninitialized.cpp
+++ b/clang/test/Sema/attr-loader-uninitialized.cpp
@@ -9,6 +9,10 @@
 extern int external_rejected __attribute__((loader_uninitialized));
 // expected-error@-1 {{variable 'external_rejected' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
 
+struct S;
+extern S incomplete_external_rejected __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable 'incomplete_external_rejected' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
+
 int noargs __attribute__((loader_uninitialized(0)));
 // expected-error@-1 {{'loader_uninitialized' attribute takes no arguments}}
 
@@ -58,3 +62,12 @@
 
 nontrivial needs_trivial_ctor __attribute__((loader_uninitialized));
 // expected-error@-1 {{variable with 'loader_uninitialized' attribute must have a trivial default constructor}}
+
+struct Incomplete;
+Incomplete incomplete __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable has incomplete type 'Incomplete'}}
+// expected-note@-3 {{forward declaration of 'Incomplete'}}
+
+struct Incomplete s_incomplete __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable has incomplete type 'struct Incomplete'}}
+// expected-note@-7 {{forward declaration of 'Incomplete'}}