diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -3673,6 +3673,28 @@
                               D->getInClassInitStyle()))
     return ToField;
 
+  // FieldDecl::isZeroSize may need to check these.
+  if (const Attr *FromAttr = D->getAttr<NoUniqueAddressAttr>()) {
+    if (auto ToAttrOrErr = Importer.Import(FromAttr))
+      ToField->addAttr(*ToAttrOrErr);
+    else
+      return ToAttrOrErr.takeError();
+    RecordType *FromRT =
+        const_cast<RecordType *>(D->getType()->getAs<RecordType>());
+    // Is this field a struct? FieldDecl::isZeroSize will need its definition.
+    if (FromRT) {
+      RecordDecl *FromRD = FromRT->getDecl();
+      RecordType *ToRT =
+          const_cast<RecordType *>(ToField->getType()->getAs<RecordType>());
+      assert(ToRT && "RecordType import has different type");
+      RecordDecl *ToRD = ToRT->getDecl();
+      if (FromRD->isCompleteDefinition() && !ToRD->isCompleteDefinition()) {
+        if (Error Err = ImportDefinition(FromRD, ToRD, IDK_Basic))
+          return std::move(Err);
+      }
+    }
+  }
+
   ToField->setAccess(D->getAccess());
   ToField->setLexicalDeclContext(LexicalDC);
   if (ToInitializer)
@@ -8445,6 +8467,8 @@
   // Make sure that ImportImpl registered the imported decl.
   assert(ImportedDecls.count(FromD) != 0 && "Missing call to MapImported?");
 
+  // There may have been NoUniqueAddressAttr for FieldDecl::isZeroSize.
+  ToD->dropAttrs();
   if (FromD->hasAttrs())
     for (const Attr *FromAttr : FromD->getAttrs()) {
       auto ToAttrOrErr = Import(FromAttr);
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -6323,6 +6323,33 @@
             ToD->getTemplateSpecializationKind());
 }
 
+TEST_P(ASTImporterOptionSpecificTestBase, ImportNoUniqueAddress) {
+  Decl *FromTU = getTuDecl(
+      R"(
+      struct A {};
+      struct B {
+        [[no_unique_address]] A a;
+      };
+      struct C : B {
+        char c;
+      } c;
+      )", Lang_CXX20);
+
+  // It does not fail even without the patch!
+  auto *BFromD = FirstDeclMatcher<CXXRecordDecl>().match(
+      FromTU, cxxRecordDecl(hasName("B")));
+  ASSERT_TRUE(BFromD);
+  auto *BToD = Import(BFromD, Lang_CXX20);
+  EXPECT_TRUE(BToD);
+
+  // It does not fail even without the patch!
+  auto *CFromD = FirstDeclMatcher<CXXRecordDecl>().match(
+      FromTU, cxxRecordDecl(hasName("C")));
+  ASSERT_TRUE(CFromD);
+  auto *CToD = Import(CFromD, Lang_CXX20);
+  EXPECT_TRUE(CToD);
+}
+
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ASTImporterLookupTableTest,
                         DefaultTestValuesForRunOptions, );