Index: test/Index/print-type-size.c
===================================================================
--- /dev/null
+++ test/Index/print-type-size.c
@@ -0,0 +1,31 @@
+// RUN: c-index-test -test-print-type-size %s | FileCheck %s
+
+struct Foo {
+  int size;
+  // CHECK: FieldDecl=size:4:7 (Definition) [type=int] [typekind=Int] [sizeof=4] [alignof=4] [offsetof=0]
+  void *data[];
+  // CHECK: FieldDecl=data:6:9 (Definition) [type=void *[]] [typekind=IncompleteArray] [sizeof=-2] [alignof=8] [offsetof=64]
+};
+
+struct Bar {
+  int size;
+  // CHECK: FieldDecl=size:11:7 (Definition) [type=int] [typekind=Int] [sizeof=4] [alignof=4] [offsetof=0]
+  struct {
+    int dummy;
+    // CHECK: FieldDecl=dummy:14:9 (Definition) [type=int] [typekind=Int] [sizeof=4] [alignof=4] [offsetof=64/0]
+    void *data[];
+    // CHECK: FieldDecl=data:16:11 (Definition) [type=void *[]] [typekind=IncompleteArray] [sizeof=-2] [alignof=8] [offsetof=128/64]
+  };
+};
+
+struct Baz {
+  int size;
+  // CHECK: FieldDecl=size:22:7 (Definition) [type=int] [typekind=Int] [sizeof=4] [alignof=4] [offsetof=0]
+  union {
+    void *data1[];
+    // CHECK: FieldDecl=data1:25:11 (Definition) [type=void *[]] [typekind=IncompleteArray] [sizeof=-2] [alignof=8] [offsetof=64/0]
+    void *data2[];
+    // CHECK: FieldDecl=data2:27:11 (Definition) [type=void *[]] [typekind=IncompleteArray] [sizeof=-2] [alignof=8] [offsetof=64/0]
+  };
+};
+
Index: tools/libclang/CXType.cpp
===================================================================
--- tools/libclang/CXType.cpp
+++ tools/libclang/CXType.cpp
@@ -885,6 +885,10 @@
   return result;
 }
 
+static bool isIncompleteTypeWithAlignment(QualType QT) {
+  return QT->isIncompleteArrayType() || !QT->isIncompleteType();
+}
+
 long long clang_Type_getAlignOf(CXType T) {
   if (T.kind == CXType_Invalid)
     return CXTypeLayoutError_Invalid;
@@ -895,7 +899,7 @@
   // [expr.alignof] p3: if reference type, return size of referenced type
   if (QT->isReferenceType())
     QT = QT.getNonReferenceType();
-  if (QT->isIncompleteType())
+  if (!isIncompleteTypeWithAlignment(QT))
     return CXTypeLayoutError_Incomplete;
   if (QT->isDependentType())
     return CXTypeLayoutError_Dependent;
@@ -950,10 +954,14 @@
   return Ctx.getTypeSizeInChars(QT).getQuantity();
 }
 
+static bool isTypeIncompleteForLayout(QualType QT) {
+  return QT->isIncompleteType() && !QT->isIncompleteArrayType();
+}
+
 static long long visitRecordForValidation(const RecordDecl *RD) {
   for (const auto *I : RD->fields()){
     QualType FQT = I->getType();
-    if (FQT->isIncompleteType())
+    if (isTypeIncompleteForLayout(FQT))
       return CXTypeLayoutError_Incomplete;
     if (FQT->isDependentType())
       return CXTypeLayoutError_Dependent;