Index: include/clang/ASTMatchers/ASTMatchers.h
===================================================================
--- include/clang/ASTMatchers/ASTMatchers.h
+++ include/clang/ASTMatchers/ASTMatchers.h
@@ -5486,6 +5486,22 @@
 /// }
 /// int z;
 /// \endcode
+///
+/// From clang/Basic/Linkage.h:
+/// > UniqueExternalLinkage:
+/// > External linkage within a unique namespace.
+/// > From the language perspective, these entities have external
+/// > linkage. However, since they reside in an anonymous namespace,
+/// > their names are unique to this translation unit, which is
+/// > equivalent to having internal linkage from the code-generation
+/// > point of view.
+///
+/// Example matches f (matcher = functionDecl(hasExternalFormalLinkage()))
+/// \code
+/// namespace {
+/// void f() {}
+/// }
+/// \endcode
 AST_MATCHER(NamedDecl, hasExternalFormalLinkage) {
   return Node.hasExternalFormalLinkage();
 }
Index: unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
===================================================================
--- unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
@@ -1939,12 +1939,18 @@
 
 TEST(HasExternalFormalLinkage, Basic) {
   EXPECT_TRUE(matches("int a = 0;", namedDecl(hasExternalFormalLinkage())));
-  EXPECT_FALSE(
-      matches("static int a = 0;", namedDecl(hasExternalFormalLinkage())));
-  EXPECT_FALSE(matches("static void f(void) { int a = 0; }",
-                       namedDecl(hasExternalFormalLinkage())));
+  EXPECT_TRUE(
+      notMatches("static int a = 0;", namedDecl(hasExternalFormalLinkage())));
+  EXPECT_TRUE(notMatches("static void f(void) { int a = 0; }",
+                         namedDecl(hasExternalFormalLinkage())));
   EXPECT_TRUE(matches("void f(void) { int a = 0; }",
                       namedDecl(hasExternalFormalLinkage())));
+
+  // Despite having internal semantic linkage, the anonymous namespace member
+  // has external linkage because the member has a unique name in all
+  // translation units.
+  EXPECT_TRUE(matches("namespace { int a = 0; }",
+                      namedDecl(hasExternalFormalLinkage())));
 }
 
 } // namespace ast_matchers