Index: lib/Format/UsingDeclarationsSorter.cpp
===================================================================
--- lib/Format/UsingDeclarationsSorter.cpp
+++ lib/Format/UsingDeclarationsSorter.cpp
@@ -74,37 +74,40 @@
 }
 
 void endUsingDeclarationBlock(
-    SmallVectorImpl<UsingDeclaration> *UsingDeclarations,
+    SmallVectorImpl<UsingDeclaration> *UsingDeclarations, bool *BlockAffected,
     const SourceManager &SourceMgr, tooling::Replacements *Fixes) {
-  SmallVector<UsingDeclaration, 4> SortedUsingDeclarations(
-      UsingDeclarations->begin(), UsingDeclarations->end());
-  std::stable_sort(SortedUsingDeclarations.begin(),
-                   SortedUsingDeclarations.end());
-  for (size_t I = 0, E = UsingDeclarations->size(); I < E; ++I) {
-    if ((*UsingDeclarations)[I].Line == SortedUsingDeclarations[I].Line)
-      continue;
-    auto Begin = (*UsingDeclarations)[I].Line->First->Tok.getLocation();
-    auto End = (*UsingDeclarations)[I].Line->Last->Tok.getEndLoc();
-    auto SortedBegin =
-        SortedUsingDeclarations[I].Line->First->Tok.getLocation();
-    auto SortedEnd = SortedUsingDeclarations[I].Line->Last->Tok.getEndLoc();
-    StringRef Text(SourceMgr.getCharacterData(SortedBegin),
-                   SourceMgr.getCharacterData(SortedEnd) -
-                       SourceMgr.getCharacterData(SortedBegin));
-    DEBUG({
-      StringRef OldText(SourceMgr.getCharacterData(Begin),
-                        SourceMgr.getCharacterData(End) -
-                            SourceMgr.getCharacterData(Begin));
-      llvm::dbgs() << "Replacing '" << OldText << "' with '" << Text << "'\n";
-    });
-    auto Range = CharSourceRange::getCharRange(Begin, End);
-    auto Err = Fixes->add(tooling::Replacement(SourceMgr, Range, Text));
-    if (Err) {
-      llvm::errs() << "Error while sorting using declarations: "
-                   << llvm::toString(std::move(Err)) << "\n";
+  if (*BlockAffected) {
+    SmallVector<UsingDeclaration, 4> SortedUsingDeclarations(
+        UsingDeclarations->begin(), UsingDeclarations->end());
+    std::stable_sort(SortedUsingDeclarations.begin(),
+                     SortedUsingDeclarations.end());
+    for (size_t I = 0, E = UsingDeclarations->size(); I < E; ++I) {
+      if ((*UsingDeclarations)[I].Line == SortedUsingDeclarations[I].Line)
+        continue;
+      auto Begin = (*UsingDeclarations)[I].Line->First->Tok.getLocation();
+      auto End = (*UsingDeclarations)[I].Line->Last->Tok.getEndLoc();
+      auto SortedBegin =
+          SortedUsingDeclarations[I].Line->First->Tok.getLocation();
+      auto SortedEnd = SortedUsingDeclarations[I].Line->Last->Tok.getEndLoc();
+      StringRef Text(SourceMgr.getCharacterData(SortedBegin),
+                     SourceMgr.getCharacterData(SortedEnd) -
+                         SourceMgr.getCharacterData(SortedBegin));
+      DEBUG({
+        StringRef OldText(SourceMgr.getCharacterData(Begin),
+                          SourceMgr.getCharacterData(End) -
+                              SourceMgr.getCharacterData(Begin));
+        llvm::dbgs() << "Replacing '" << OldText << "' with '" << Text << "'\n";
+      });
+      auto Range = CharSourceRange::getCharRange(Begin, End);
+      auto Err = Fixes->add(tooling::Replacement(SourceMgr, Range, Text));
+      if (Err) {
+        llvm::errs() << "Error while sorting using declarations: "
+                     << llvm::toString(std::move(Err)) << "\n";
+      }
     }
   }
   UsingDeclarations->clear();
+  *BlockAffected = false;
 }
 
 } // namespace
@@ -121,23 +124,29 @@
                                         AnnotatedLines.end());
   tooling::Replacements Fixes;
   SmallVector<UsingDeclaration, 4> UsingDeclarations;
+  bool BlockAffected = false;
   for (size_t I = 0, E = AnnotatedLines.size(); I != E; ++I) {
-    if (!AnnotatedLines[I]->Affected || AnnotatedLines[I]->InPPDirective ||
+    if (AnnotatedLines[I]->InPPDirective ||
         !AnnotatedLines[I]->startsWith(tok::kw_using) ||
         AnnotatedLines[I]->First->Finalized) {
-      endUsingDeclarationBlock(&UsingDeclarations, SourceMgr, &Fixes);
+      endUsingDeclarationBlock(&UsingDeclarations, &BlockAffected, SourceMgr,
+                               &Fixes);
       continue;
     }
     if (AnnotatedLines[I]->First->NewlinesBefore > 1)
-      endUsingDeclarationBlock(&UsingDeclarations, SourceMgr, &Fixes);
+      endUsingDeclarationBlock(&UsingDeclarations, &BlockAffected, SourceMgr,
+                               &Fixes);
     std::string Label = computeUsingDeclarationLabel(AnnotatedLines[I]->First);
     if (Label.empty()) {
-      endUsingDeclarationBlock(&UsingDeclarations, SourceMgr, &Fixes);
+      endUsingDeclarationBlock(&UsingDeclarations, &BlockAffected, SourceMgr,
+                               &Fixes);
       continue;
     }
     UsingDeclarations.push_back(UsingDeclaration(AnnotatedLines[I], Label));
+    BlockAffected = BlockAffected || AnnotatedLines[I]->Affected;
   }
-  endUsingDeclarationBlock(&UsingDeclarations, SourceMgr, &Fixes);
+  endUsingDeclarationBlock(&UsingDeclarations, &BlockAffected, SourceMgr,
+                           &Fixes);
   return Fixes;
 }
 
Index: unittests/Format/UsingDeclarationsSorterTest.cpp
===================================================================
--- unittests/Format/UsingDeclarationsSorterTest.cpp
+++ unittests/Format/UsingDeclarationsSorterTest.cpp
@@ -291,13 +291,41 @@
 }
 
 TEST_F(UsingDeclarationsSorterTest, SortsPartialRangeOfUsingDeclarations) {
-  EXPECT_EQ("using b;\n"
-            "using a;\n"
+  // Sorts the whole block of using declarations surrounding the range.
+  EXPECT_EQ("using a;\n"
+            "using b;\n"
             "using c;",
             sortUsingDeclarations("using b;\n"
                                   "using c;\n" // starts at offset 10
                                   "using a;",
                                   {tooling::Range(10, 15)}));
+  EXPECT_EQ("using a;\n"
+            "using b;\n"
+            "using c;\n"
+            "using A = b;",
+            sortUsingDeclarations("using b;\n"
+                                  "using c;\n" // starts at offset 10
+                                  "using a;\n"
+                                  "using A = b;",
+                                  {tooling::Range(10, 15)}));
+
+  EXPECT_EQ("using d;\n"
+            "using c;\n"
+            "\n"
+            "using a;\n"
+            "using b;\n"
+            "\n"
+            "using f;\n"
+            "using e;",
+            sortUsingDeclarations("using d;\n"
+                                  "using c;\n"
+                                  "\n"
+                                  "using b;\n" // starts at offset 19
+                                  "using a;\n"
+                                  "\n"
+                                  "using f;\n"
+                                  "using e;",
+                                  {tooling::Range(19, 1)}));
 }
 
 } // end namespace