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
@@ -4018,6 +4018,7 @@
                               D->getStorageClass()))
     return ToVar;
 
+  ToVar->setTSCSpec(D->getTSCSpec());
   ToVar->setQualifierInfo(ToQualifierLoc);
   ToVar->setAccess(D->getAccess());
   ToVar->setLexicalDeclContext(LexicalDC);
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
@@ -3480,6 +3480,20 @@
 
 struct ImportVariables : ASTImporterOptionSpecificTestBase {};
 
+TEST_P(ImportVariables, ImportedVarDeclPreservesThreadLocalStorage) {
+  Decl *FromTU =
+      getTuDecl("thread_local int declToImport;", Lang_CXX11, "input1.cc");
+
+  auto *FromDWithTLS = FirstDeclMatcher<VarDecl>().match(
+      FromTU, varDecl(hasThreadStorageDuration()));
+  ASSERT_TRUE(FromDWithTLS);
+  ASSERT_EQ(SD_Thread, FromDWithTLS->getStorageDuration());
+
+  const auto *ToD = Import(FromDWithTLS, Lang_CXX11);
+  ASSERT_TRUE(ToD);
+  EXPECT_EQ(SD_Thread, ToD->getStorageDuration());
+}
+
 TEST_P(ImportVariables, ImportOfOneDeclBringsInTheWholeChain) {
   Decl *FromTU = getTuDecl(
       R"(