Index: cfe/trunk/lib/Format/Format.cpp
===================================================================
--- cfe/trunk/lib/Format/Format.cpp
+++ cfe/trunk/lib/Format/Format.cpp
@@ -1041,11 +1041,12 @@
 
   // Iterate through all lines and remove any empty (nested) namespaces.
   void checkEmptyNamespace(SmallVectorImpl<AnnotatedLine *> &AnnotatedLines) {
+    std::set<unsigned> DeletedLines;
     for (unsigned i = 0, e = AnnotatedLines.size(); i != e; ++i) {
       auto &Line = *AnnotatedLines[i];
       if (Line.startsWith(tok::kw_namespace) ||
           Line.startsWith(tok::kw_inline, tok::kw_namespace)) {
-        checkEmptyNamespace(AnnotatedLines, i, i);
+        checkEmptyNamespace(AnnotatedLines, i, i, DeletedLines);
       }
     }
 
@@ -1063,7 +1064,8 @@
   // sets \p NewLine to the last line checked.
   // Returns true if the current namespace is empty.
   bool checkEmptyNamespace(SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
-                           unsigned CurrentLine, unsigned &NewLine) {
+                           unsigned CurrentLine, unsigned &NewLine,
+                           std::set<unsigned> &DeletedLines) {
     unsigned InitLine = CurrentLine, End = AnnotatedLines.size();
     if (Style.BraceWrapping.AfterNamespace) {
       // If the left brace is in a new line, we should consume it first so that
@@ -1083,7 +1085,8 @@
       if (AnnotatedLines[CurrentLine]->startsWith(tok::kw_namespace) ||
           AnnotatedLines[CurrentLine]->startsWith(tok::kw_inline,
                                                   tok::kw_namespace)) {
-        if (!checkEmptyNamespace(AnnotatedLines, CurrentLine, NewLine))
+        if (!checkEmptyNamespace(AnnotatedLines, CurrentLine, NewLine,
+                                 DeletedLines))
           return false;
         CurrentLine = NewLine;
         continue;
@@ -1208,8 +1211,6 @@
 
   // Tokens to be deleted.
   std::set<FormatToken *, FormatTokenLess> DeletedTokens;
-  // The line numbers of lines to be deleted.
-  std::set<unsigned> DeletedLines;
 };
 
 struct IncludeDirective {
Index: cfe/trunk/unittests/Format/CleanupTest.cpp
===================================================================
--- cfe/trunk/unittests/Format/CleanupTest.cpp
+++ cfe/trunk/unittests/Format/CleanupTest.cpp
@@ -119,6 +119,24 @@
   EXPECT_EQ(Expected, Result);
 }
 
+TEST_F(CleanupTest, EmptyNamespaceAroundConditionalCompilation) {
+  std::string Code = "#ifdef A\n"
+                     "int a;\n"
+                     "int b;\n"
+                     "#else\n"
+                     "#endif\n"
+                     "namespace {}";
+  std::string Expected = "#ifdef A\n"
+                         "int a;\n"
+                         "int b;\n"
+                         "#else\n"
+                         "#endif\n";
+  std::vector<tooling::Range> Ranges(1, tooling::Range(0, Code.size()));
+  FormatStyle Style = getLLVMStyle();
+  std::string Result = cleanup(Code, Ranges, Style);
+  EXPECT_EQ(Expected, Result);
+}
+
 TEST_F(CleanupTest, CtorInitializationSimpleRedundantComma) {
   std::string Code = "class A {\nA() : , {} };";
   std::string Expected = "class A {\nA()  {} };";