Index: clang/lib/Format/NamespaceEndCommentsFixer.cpp
===================================================================
--- clang/lib/Format/NamespaceEndCommentsFixer.cpp
+++ clang/lib/Format/NamespaceEndCommentsFixer.cpp
@@ -24,11 +24,11 @@
 namespace {
 // Computes the name of a namespace given the namespace token.
 // Returns "" for anonymous namespace.
-std::string computeName(const FormatToken *NamespaceTok) {
+bool computeName(const FormatToken *NamespaceTok, std::string &name) {
   assert(NamespaceTok &&
          NamespaceTok->isOneOf(tok::kw_namespace, TT_NamespaceMacro) &&
          "expecting a namespace token");
-  std::string name = "";
+  name = "";
   const FormatToken *Tok = NamespaceTok->getNextNonComment();
   if (NamespaceTok->is(TT_NamespaceMacro)) {
     // Collects all the non-comment tokens between opening parenthesis
@@ -55,10 +55,13 @@
       name += Tok->TokenText;
       if (Tok->is(tok::kw_inline))
         name += " ";
+      // Namespace alias
+      if (Tok->isOneOf(tok::equal, tok::semi))
+        return false;
       Tok = Tok->getNextNonComment();
     }
   }
-  return name;
+  return true;
 }
 
 std::string computeEndCommentText(StringRef NamespaceName, bool AddNewline,
@@ -242,7 +245,13 @@
     }
     if (StartLineIndex == SIZE_MAX)
       StartLineIndex = EndLine->MatchingOpeningBlockLineIndex;
-    std::string NamespaceName = computeName(NamespaceTok);
+
+    std::string NamespaceName;
+    if (!computeName(NamespaceTok, NamespaceName)) {
+      // Its likely a namespace alias.
+      continue;
+    }
+
     if (Style.CompactNamespaces) {
       if (CompactedNamespacesCount == 0)
         NamespaceTokenText = NamespaceTok->TokenText;
Index: clang/unittests/Format/NamespaceEndCommentsFixerTest.cpp
===================================================================
--- clang/unittests/Format/NamespaceEndCommentsFixerTest.cpp
+++ clang/unittests/Format/NamespaceEndCommentsFixerTest.cpp
@@ -1185,6 +1185,22 @@
                                     "}\n",
                                     Style));
 }
+
+TEST_F(ShortNamespaceLinesTest, NameSpaceAlias) {
+  auto Style = getLLVMStyle();
+
+  EXPECT_EQ("namespace n = nn;\n"
+            "{\n"
+            "  int i;\n"
+            "  int j;\n"
+            "}\n",
+            fixNamespaceEndComments("namespace n = nn;\n"
+                                    "{\n"
+                                    "  int i;\n"
+                                    "  int j;\n"
+                                    "}\n",
+                                    Style));
+}
 } // end namespace
 } // end namespace format
 } // end namespace clang