Index: lib/AST/DeclBase.cpp
===================================================================
--- lib/AST/DeclBase.cpp
+++ lib/AST/DeclBase.cpp
@@ -1350,6 +1350,32 @@
           (D->NextInContextAndBits.getPointer() || D == LastDecl));
 }
 
+/// shouldBeHidden - Determine whether a declaration which was declared
+/// within its semantic context should be invisible to qualified name lookup.
+static bool shouldBeHidden(NamedDecl *D) {
+  // Skip unnamed declarations.
+  if (!D->getDeclName())
+    return true;
+
+  // Skip entities that can't be found by name lookup into a particular
+  // context.
+  if ((D->getIdentifierNamespace() == 0 && !isa<UsingDirectiveDecl>(D)) ||
+      D->isTemplateParameter())
+    return true;
+
+  // Skip template specializations.
+  // FIXME: This feels like a hack. Should DeclarationName support
+  // template-ids, or is there a better way to keep specializations
+  // from being visible?
+  if (isa<ClassTemplateSpecializationDecl>(D))
+    return true;
+  if (auto *FD = dyn_cast<FunctionDecl>(D))
+    if (FD->isFunctionTemplateSpecialization())
+      return true;
+
+  return false;
+}
+
 void DeclContext::removeDecl(Decl *D) {
   assert(D->getLexicalDeclContext() == this &&
          "decl being removed from non-lexical context");
@@ -1372,7 +1398,7 @@
       }
     }
   }
-  
+
   // Mark that D is no longer in the decl chain.
   D->NextInContextAndBits.setPointer(nullptr);
 
@@ -1380,8 +1406,14 @@
   if (isa<NamedDecl>(D)) {
     auto *ND = cast<NamedDecl>(D);
 
+    // Do not try to remove the declaration if that is invisible to qualified
+    // lookup.  E.g. template specializations are skipped.
+    if (shouldBeHidden(ND))
+      return;
+
     // Remove only decls that have a name
-    if (!ND->getDeclName()) return;
+    if (!ND->getDeclName())
+      return;
 
     auto *DC = D->getDeclContext();
     do {
@@ -1438,32 +1470,6 @@
         makeDeclVisibleInContextWithFlags(ND, true, true);
 }
 
-/// shouldBeHidden - Determine whether a declaration which was declared
-/// within its semantic context should be invisible to qualified name lookup.
-static bool shouldBeHidden(NamedDecl *D) {
-  // Skip unnamed declarations.
-  if (!D->getDeclName())
-    return true;
-
-  // Skip entities that can't be found by name lookup into a particular
-  // context.
-  if ((D->getIdentifierNamespace() == 0 && !isa<UsingDirectiveDecl>(D)) ||
-      D->isTemplateParameter())
-    return true;
-
-  // Skip template specializations.
-  // FIXME: This feels like a hack. Should DeclarationName support
-  // template-ids, or is there a better way to keep specializations
-  // from being visible?
-  if (isa<ClassTemplateSpecializationDecl>(D))
-    return true;
-  if (auto *FD = dyn_cast<FunctionDecl>(D))
-    if (FD->isFunctionTemplateSpecialization())
-      return true;
-
-  return false;
-}
-
 /// buildLookup - Build the lookup data structure with all of the
 /// declarations in this DeclContext (and any other contexts linked
 /// to it or transparent contexts nested within it) and return it.
Index: unittests/AST/ASTImporterTest.cpp
===================================================================
--- unittests/AST/ASTImporterTest.cpp
+++ unittests/AST/ASTImporterTest.cpp
@@ -1797,5 +1797,38 @@
                  compoundStmt(has(callExpr(has(unresolvedMemberExpr())))))))));
 }
 
+struct DeclContextTest : ASTImporterTestBase {};
+
+TEST_P(DeclContextTest, removeDeclOfClassTemplateSpecialization) {
+  Decl *TU = getTuDecl(
+      R"(
+      namespace NS {
+
+      template <typename T>
+      struct S {};
+      template struct S<int>;
+
+      inline namespace INS {
+        template <typename T>
+        struct S {};
+        template struct S<int>;
+      }
+
+      }
+      )", Lang_CXX11, "input0.cc");
+  auto *NS = FirstDeclMatcher<NamespaceDecl>().match(
+      TU, namespaceDecl());
+  auto *Spec = FirstDeclMatcher<ClassTemplateSpecializationDecl>().match(
+      TU, classTemplateSpecializationDecl());
+  ASSERT_TRUE(NS->containsDecl(Spec));
+
+  NS->removeDecl(Spec);
+  EXPECT_FALSE(NS->containsDecl(Spec));
+}
+
+INSTANTIATE_TEST_CASE_P(
+    ParameterizedTests, DeclContextTest,
+    ::testing::Values(ArgVector(), ArgVector{"-fdelayed-template-parsing"}),);
+
 } // end namespace ast_matchers
 } // end namespace clang