Index: llvm/include/llvm-c/lto.h
===================================================================
--- llvm/include/llvm-c/lto.h
+++ llvm/include/llvm-c/lto.h
@@ -46,7 +46,7 @@
  * @{
  */
 
-#define LTO_API_VERSION 27
+#define LTO_API_VERSION 28
 
 /**
  * \since prior to LTO_API_VERSION=3
@@ -527,7 +527,24 @@
 lto_api_version(void);
 
 /**
- * Sets options to help debug codegen bugs.
+ * Parses options immediately, making them available as early as possible. For
+ * example during executing codegen::InitTargetOptionsFromCodeGenFlags. Since
+ * parsing shud only happen once, only one of lto_codegen_debug_options or
+ * lto_codegen_debug_options_early should be called.
+ *
+ * This function takes one or more options separated by spaces.
+ * Warning: passing file paths through this function may confuse the argument
+ * parser if the paths contain spaces.
+ *
+ * \since LTO_API_VERSION=28
+ */
+extern void
+lto_codegen_debug_options_early(const char *opt);
+
+/**
+ * Sets options to help debug codegen bugs. Since parsing shud only happen once,
+ * only one of lto_codegen_debug_options or lto_codegen_debug_options_early
+ * should be called.
  *
  * This function takes one or more options separated by spaces.
  * Warning: passing file paths through this function may confuse the argument
Index: llvm/include/llvm/LTO/legacy/LTOCodeGenerator.h
===================================================================
--- llvm/include/llvm/LTO/legacy/LTOCodeGenerator.h
+++ llvm/include/llvm/LTO/legacy/LTOCodeGenerator.h
@@ -240,5 +240,9 @@
 
   lto::Config Config;
 };
+
+/// A convenience function that calls cl::ParseCommandLineOptions on the given
+/// set of options.
+void parseCommandLineOptions(std::vector<std::string> &Options);
 }
 #endif
Index: llvm/lib/LTO/LTOCodeGenerator.cpp
===================================================================
--- llvm/lib/LTO/LTOCodeGenerator.cpp
+++ llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -598,11 +598,16 @@
 }
 
 void LTOCodeGenerator::parseCodeGenDebugOptions() {
+  if (!CodegenOptions.empty())
+    llvm::parseCommandLineOptions(CodegenOptions);
+}
+
+void llvm::parseCommandLineOptions(std::vector<std::string> &Options) {
   // if options were requested, set them
-  if (!CodegenOptions.empty()) {
+  if (!Options.empty()) {
     // ParseCommandLineOptions() expects argv[0] to be program name.
     std::vector<const char *> CodegenArgv(1, "libLLVMLTO");
-    for (std::string &Arg : CodegenOptions)
+    for (std::string &Arg : Options)
       CodegenArgv.push_back(Arg.c_str());
     cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
   }
Index: llvm/tools/lto/lto.cpp
===================================================================
--- llvm/tools/lto/lto.cpp
+++ llvm/tools/lto/lto.cpp
@@ -66,6 +66,9 @@
 // Holds the command-line option parsing state of the LTO module.
 static bool parsedOptions = false;
 
+// Set to true if options were parsed early.
+static bool parsedOptionsEarly = false;
+
 static LLVMContext *LTOContext = nullptr;
 
 struct LTOToolDiagnosticHandler : public DiagnosticHandler {
@@ -460,7 +463,22 @@
   return !unwrap(cg)->compile_to_file(name);
 }
 
+void lto_codegen_debug_options_early(const char *opt) {
+  if (opt) {
+    // Need to put each suboption in a null-terminated string before passing to
+    // parseCommandLineOptions().
+    std::vector<std::string> Options;
+    for (std::pair<StringRef, StringRef> o = getToken(opt); !o.first.empty();
+         o = getToken(o.second))
+      Options.push_back(o.first.str());
+
+    llvm::parseCommandLineOptions(Options);
+    parsedOptionsEarly = true;
+  }
+}
+
 void lto_codegen_debug_options(lto_code_gen_t cg, const char *opt) {
+  assert(!parsedOptionsEarly && "early option processing already happened");
   SmallVector<StringRef, 4> Options;
   for (std::pair<StringRef, StringRef> o = getToken(opt); !o.first.empty();
        o = getToken(o.second))