Index: cfe/trunk/lib/Format/SortJavaScriptImports.cpp
===================================================================
--- cfe/trunk/lib/Format/SortJavaScriptImports.cpp
+++ cfe/trunk/lib/Format/SortJavaScriptImports.cpp
@@ -170,12 +170,25 @@
     if (ReferencesInOrder && SymbolsInOrder)
       return Result;
 
+    SourceRange InsertionPoint = References[0].Range;
+    InsertionPoint.setEnd(References[References.size() - 1].Range.getEnd());
+
+    // The loop above might collapse previously existing line breaks between
+    // import blocks, and thus shrink the file. SortIncludes must not shrink
+    // overall source length as there is currently no re-calculation of ranges
+    // after applying source sorting.
+    // This loop just backfills trailing spaces after the imports, which are
+    // harmless and will be stripped by the subsequent formatting pass.
+    // TODO: A better long term fix is to re-calculate Ranges after sorting.
+    unsigned PreviousSize = getSourceText(InsertionPoint).size();
+    while (ReferencesText.size() < PreviousSize) {
+      ReferencesText += " ";
+    }
+
     // Separate references from the main code body of the file.
     if (FirstNonImportLine && FirstNonImportLine->First->NewlinesBefore < 2)
       ReferencesText += "\n";
 
-    SourceRange InsertionPoint = References[0].Range;
-    InsertionPoint.setEnd(References[References.size() - 1].Range.getEnd());
     DEBUG(llvm::dbgs() << "Replacing imports:\n"
                        << getSourceText(InsertionPoint) << "\nwith:\n"
                        << ReferencesText << "\n");
Index: cfe/trunk/unittests/Format/SortImportsTestJS.cpp
===================================================================
--- cfe/trunk/unittests/Format/SortImportsTestJS.cpp
+++ cfe/trunk/unittests/Format/SortImportsTestJS.cpp
@@ -223,6 +223,19 @@
              24, 30);
 }
 
+TEST_F(SortImportsTestJS, SortingCanShrink) {
+  // Sort excluding a suffix.
+  verifySort("import {B} from 'a';\n"
+             "import {A} from 'b';\n"
+             "\n"
+             "1;",
+             "import {A} from 'b';\n"
+             "\n"
+             "import {B} from 'a';\n"
+             "\n"
+             "1;");
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang