Index: clang/lib/Format/FormatToken.h
===================================================================
--- clang/lib/Format/FormatToken.h
+++ clang/lib/Format/FormatToken.h
@@ -102,7 +102,9 @@
   TYPE(MacroBlockBegin)                                                        \
   TYPE(MacroBlockEnd)                                                          \
   TYPE(ModulePartitionColon)                                                   \
+  TYPE(NamespaceLBrace)                                                        \
   TYPE(NamespaceMacro)                                                         \
+  TYPE(NamespaceRBrace)                                                        \
   TYPE(NonNullAssertion)                                                       \
   TYPE(NullCoalescingEqual)                                                    \
   TYPE(NullCoalescingOperator)                                                 \
Index: clang/lib/Format/UnwrappedLineParser.cpp
===================================================================
--- clang/lib/Format/UnwrappedLineParser.cpp
+++ clang/lib/Format/UnwrappedLineParser.cpp
@@ -805,6 +805,9 @@
     return IfLBrace;
   }
 
+  if (FormatTok->is(tok::r_brace) && Tok->is(TT_NamespaceLBrace))
+    FormatTok->setFinalizedType(TT_NamespaceRBrace);
+
   const bool IsFunctionRBrace =
       FormatTok->is(tok::r_brace) && Tok->is(TT_FunctionLBrace);
 
@@ -2958,6 +2961,9 @@
     }
   }
   if (FormatTok->is(tok::l_brace)) {
+    FormatToken *LBrace = FormatTok;
+    LBrace->setFinalizedType(TT_NamespaceLBrace);
+
     if (ShouldBreakBeforeBrace(Style, InitialToken))
       addUnwrappedLine();
 
Index: clang/lib/Format/WhitespaceManager.cpp
===================================================================
--- clang/lib/Format/WhitespaceManager.cpp
+++ clang/lib/Format/WhitespaceManager.cpp
@@ -1081,11 +1081,10 @@
 
     if (i + 1 != e && Changes[i + 1].ContinuesPPDirective)
       ChangeMaxColumn -= 2;
-    // If this comment follows an } in column 0, it probably documents the
-    // closing of a namespace and we don't want to align it.
-    bool FollowsRBraceInColumn0 = i > 0 && Changes[i].NewlinesBefore == 0 &&
-                                  Changes[i - 1].Tok->is(tok::r_brace) &&
-                                  Changes[i - 1].StartOfTokenColumn == 0;
+
+    // We don't want to align namespace end comments.
+    bool DontAlignThisComment = i > 0 && Changes[i].NewlinesBefore == 0 &&
+                                Changes[i - 1].Tok->is(TT_NamespaceRBrace);
     bool WasAlignedWithStartOfNextLine = false;
     if (Changes[i].NewlinesBefore >= 1) { // A comment on its own line.
       unsigned CommentColumn = SourceMgr.getSpellingColumnNumber(
@@ -1105,7 +1104,7 @@
       }
     }
     if (Style.AlignTrailingComments.Kind == FormatStyle::TCAS_Never ||
-        FollowsRBraceInColumn0) {
+        DontAlignThisComment) {
       alignTrailingComments(StartOfSequence, i, MinColumn);
       MinColumn = ChangeMinColumn;
       MaxColumn = ChangeMinColumn;
Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -20314,7 +20314,7 @@
                "      int x;\n"
                "      };\n"
                "    } // namespace b\n"
-               "  }   // namespace a",
+               "  } // namespace a",
                WhitesmithsBraceStyle);
 
   verifyFormat("void f()\n"
Index: clang/unittests/Format/FormatTestComments.cpp
===================================================================
--- clang/unittests/Format/FormatTestComments.cpp
+++ clang/unittests/Format/FormatTestComments.cpp
@@ -3087,6 +3087,118 @@
                    Style));
 }
 
+TEST_F(FormatTestComments, DontAlignNamespaceComments) {
+  FormatStyle Style = getLLVMStyle();
+  Style.NamespaceIndentation = FormatStyle::NI_All;
+  Style.NamespaceMacros.push_back("TESTSUITE");
+  Style.ShortNamespaceLines = 0;
+
+  StringRef Input = "namespace A {\n"
+                    "  TESTSUITE(B) {\n"
+                    "    namespace C {\n"
+                    "      namespace D {} // namespace D\n"
+                    "      std::string Foo = Bar; // Comment\n"
+                    "      std::string BazString = Baz;   // C2\n"
+                    "    }          // namespace C\n"
+                    "  }\n"
+                    "} // NaMeSpAcE A";
+
+  EXPECT_TRUE(Style.FixNamespaceComments);
+  EXPECT_EQ(Style.AlignTrailingComments.Kind, FormatStyle::TCAS_Always);
+  verifyFormat("namespace A {\n"
+               "  TESTSUITE(B) {\n"
+               "    namespace C {\n"
+               "      namespace D {} // namespace D\n"
+               "      std::string Foo = Bar;       // Comment\n"
+               "      std::string BazString = Baz; // C2\n"
+               "    } // namespace C\n"
+               "  } // TESTSUITE(B)\n"
+               "} // NaMeSpAcE A",
+               Input, Style);
+
+  Style.AlignTrailingComments.Kind = FormatStyle::TCAS_Never;
+  verifyFormat("namespace A {\n"
+               "  TESTSUITE(B) {\n"
+               "    namespace C {\n"
+               "      namespace D {} // namespace D\n"
+               "      std::string Foo = Bar; // Comment\n"
+               "      std::string BazString = Baz; // C2\n"
+               "    } // namespace C\n"
+               "  } // TESTSUITE(B)\n"
+               "} // NaMeSpAcE A",
+               Input, Style);
+
+  Style.AlignTrailingComments.Kind = FormatStyle::TCAS_Leave;
+  verifyFormat("namespace A {\n"
+               "  TESTSUITE(B) {\n"
+               "    namespace C {\n"
+               "      namespace D {} // namespace D\n"
+               "      std::string Foo = Bar; // Comment\n"
+               "      std::string BazString = Baz;   // C2\n"
+               "    }          // namespace C\n"
+               "  } // TESTSUITE(B)\n"
+               "} // NaMeSpAcE A",
+               Input, Style);
+
+  Style.FixNamespaceComments = false;
+  Style.AlignTrailingComments.Kind = FormatStyle::TCAS_Always;
+  verifyFormat("namespace A {\n"
+               "  TESTSUITE(B) {\n"
+               "    namespace C {\n"
+               "      namespace D {} // namespace D\n"
+               "      std::string Foo = Bar;       // Comment\n"
+               "      std::string BazString = Baz; // C2\n"
+               "    } // namespace C\n"
+               "  }\n"
+               "} // NaMeSpAcE A",
+               Input, Style);
+
+  Style.AlignTrailingComments.Kind = FormatStyle::TCAS_Never;
+  verifyFormat("namespace A {\n"
+               "  TESTSUITE(B) {\n"
+               "    namespace C {\n"
+               "      namespace D {} // namespace D\n"
+               "      std::string Foo = Bar; // Comment\n"
+               "      std::string BazString = Baz; // C2\n"
+               "    } // namespace C\n"
+               "  }\n"
+               "} // NaMeSpAcE A",
+               Input, Style);
+
+  Style.AlignTrailingComments.Kind = FormatStyle::TCAS_Leave;
+  verifyFormat("namespace A {\n"
+               "  TESTSUITE(B) {\n"
+               "    namespace C {\n"
+               "      namespace D {} // namespace D\n"
+               "      std::string Foo = Bar; // Comment\n"
+               "      std::string BazString = Baz;   // C2\n"
+               "    }          // namespace C\n"
+               "  }\n"
+               "} // NaMeSpAcE A",
+               Input, Style);
+
+  Style.AlignTrailingComments.Kind = FormatStyle::TCAS_Always;
+  Style.FixNamespaceComments = true;
+  Input = "namespace A {\n"
+          "  int Foo;\n"
+          "  int Bar;\n"
+          "}\n"
+          "// Comment";
+
+#if 0
+  // FIXME: The following comment is aligned with the namespace comment.
+  verifyFormat("namespace A {\n"
+               "  int Foo;\n"
+               "  int Bar;\n"
+               "} // namespace A\n"
+               " // Comment",
+               Input, Style);
+#endif
+
+  Style.FixNamespaceComments = false;
+  verifyFormat(Input, Style);
+}
+
 TEST_F(FormatTestComments, AlignsBlockCommentDecorations) {
   EXPECT_EQ("/*\n"
             " */",