foo.diff

diff --git a/tools/gn/visual_studio_writer.cc b/tools/gn/visual_studio_writer.cc
index 8a8cf528fc15..59d27bf6a0be 100644
--- a/tools/gn/visual_studio_writer.cc
+++ b/tools/gn/visual_studio_writer.cc
@@ -9,6 +9,7 @@
 #include <map>
 #include <memory>
 #include <queue>
+#include <regex>
 #include <set>
 #include <string>
 
@@ -37,9 +38,10 @@
 
 namespace {
 
-struct SemicolonSeparatedWriter {
+struct SemicolonSeparatedAndSpecialCharacterConverterWriter {
   void operator()(const std::string& value, std::ostream& out) const {
-    out << value + ';';
+    std::string result = std::regex_replace(value, std::regex("<<"), "%3C%3C");
+    out << result + ';';
   }
 };
 
@@ -545,7 +547,8 @@ bool VisualStudioWriter::WriteProjectFileContents(
         std::unique_ptr<XmlElementWriter> preprocessor_definitions =
             cl_compile->SubElement("PreprocessorDefinitions");
         RecursiveTargetConfigToStream<std::string>(
-            target, &ConfigValues::defines, SemicolonSeparatedWriter(),
+            target, &ConfigValues::defines,
+            SemicolonSeparatedAndSpecialCharacterConverterWriter(),
             preprocessor_definitions->StartContent(false));
         preprocessor_definitions->Text("%(PreprocessorDefinitions)");
       }