diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index b5e6eae9f1bf7..5a19c2ea36bdf 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -327,6 +327,8 @@ Fixed Point Support in Clang
 AST Matchers
 ------------
 
+- ``isInStdNamespace`` now supports Decl declared with ``extern "C++"``.
+
 clang-format
 ------------
 
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 8163f9bdaf8d9..10fe8bb97ce66 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -402,7 +402,7 @@ bool Decl::isInAnonymousNamespace() const {
 
 bool Decl::isInStdNamespace() const {
   const DeclContext *DC = getDeclContext();
-  return DC && DC->isStdNamespace();
+  return DC && DC->getNonTransparentContext()->isStdNamespace();
 }
 
 bool Decl::isFileContextDecl() const {
diff --git a/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
index edcdae4559d97..b75da7bc1ed06 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ b/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
@@ -3637,6 +3637,11 @@ TEST_P(ASTMatchersTest, InStdNamespace) {
                       "  class vector {};"
                       "}",
                       cxxRecordDecl(hasName("vector"), isInStdNamespace())));
+
+  EXPECT_TRUE(matches("namespace std {"
+                      "  extern \"C++\" class vector {};"
+                      "}",
+                      cxxRecordDecl(hasName("vector"), isInStdNamespace())));
 }
 
 TEST_P(ASTMatchersTest, InAnonymousNamespace) {