Index: include/llvm/IR/DiagnosticInfo.h
===================================================================
--- include/llvm/IR/DiagnosticInfo.h
+++ include/llvm/IR/DiagnosticInfo.h
@@ -26,6 +26,7 @@
 class Instruction;
 class Twine;
 class Value;
+class DebugLoc;
 
 /// \brief Defines the different supported severity of a diagnostic.
 enum DiagnosticSeverity {
@@ -44,6 +45,7 @@
   DK_StackSize,
   DK_DebugMetadataVersion,
   DK_SampleProfile,
+  DK_OptimizationReport,
   DK_FirstPluginKind
 };
 
@@ -235,6 +237,52 @@
   const Twine &Msg;
 };
 
+/// Diagnostic information for optimization reports.
+class DiagnosticInfoOptimizationReport : public DiagnosticInfo {
+public:
+  DiagnosticInfoOptimizationReport(const char *PassName, const Function &Fn,
+                                   const DebugLoc &DLoc, const Twine &Msg)
+      : DiagnosticInfo(DK_OptimizationReport, DS_Remark), PassName(PassName),
+        Fn(Fn), DLoc(DLoc), Msg(Msg) {
+  }
+
+  /// \see DiagnosticInfo::print.
+  void print(DiagnosticPrinter &DP) const override;
+
+  /// Hand rolled RTTI.
+  static bool classof(const DiagnosticInfo *DI) {
+    return DI->getKind() == DK_OptimizationReport;
+  }
+
+  /// Return true if location information is available for this diagnostic.
+  bool isLocationAvailable() const;
+
+  /// Return a string with the location information for this diagnostic
+  /// in the format "file:line:col". If location information is not available,
+  /// it returns "<unknown>:0:0".
+  const StringRef getLocationStr() const;
+
+  const char *getPassName() const { return PassName; }
+  const Function &getFunction() const { return Fn; }
+  const DebugLoc &getDebugLoc() const { return DLoc; }
+  const Twine &getMsg() const { return Msg; }
+
+private:
+  /// Name of the pass that triggers this report. If this matches the
+  /// regular expression given in -Rpass=regexp, then the remark will
+  /// be emitted.
+  const char *PassName;
+
+  /// Function where this diagnostic is triggered.
+  const Function &Fn;
+
+  /// Debug location where this diagnostic is triggered.
+  const DebugLoc &DLoc;
+
+  /// Message to report.
+  const Twine &Msg;
+};
+
 } // End namespace llvm
 
 #endif
Index: include/llvm/Transforms/IPO/PassManagerBuilder.h
===================================================================
--- include/llvm/Transforms/IPO/PassManagerBuilder.h
+++ include/llvm/Transforms/IPO/PassManagerBuilder.h
@@ -16,6 +16,7 @@
 #define LLVM_TRANSFORMS_IPO_PASSMANAGERBUILDER_H
 
 #include <vector>
+#include <string>
 
 namespace llvm {
 class TargetLibraryInfo;
Index: lib/IR/DiagnosticInfo.cpp
===================================================================
--- lib/IR/DiagnosticInfo.cpp
+++ lib/IR/DiagnosticInfo.cpp
@@ -14,11 +14,13 @@
 
 #include "llvm/ADT/Twine.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
 #include "llvm/Support/Atomic.h"
 #include <string>
 
@@ -64,3 +66,24 @@
     DP << getFileName() << ": ";
   DP << getMsg();
 }
+
+bool DiagnosticInfoOptimizationReport::isLocationAvailable() const {
+  return getFunction().getParent()->getNamedMetadata("llvm.dbg.cu") != 0;
+}
+
+const StringRef DiagnosticInfoOptimizationReport::getLocationStr() const {
+  StringRef Filename("<unknown>");
+  unsigned Line = 0;
+  unsigned Column = 0;
+  if (isLocationAvailable()) {
+    DILocation DIL(getDebugLoc().getAsMDNode(getFunction().getContext()));
+    Filename = DIL.getFilename();
+    Line = DIL.getLineNumber();
+    Column = DIL.getColumnNumber();
+  }
+  return Twine(Filename + ":" + Twine(Line) + ":" + Twine(Column)).str();
+}
+
+void DiagnosticInfoOptimizationReport::print(DiagnosticPrinter &DP) const {
+  DP << getLocationStr() << ": " << getMsg();
+}
Index: lib/Transforms/IPO/Inliner.cpp
===================================================================
--- lib/Transforms/IPO/Inliner.cpp
+++ lib/Transforms/IPO/Inliner.cpp
@@ -21,6 +21,7 @@
 #include "llvm/Analysis/InlineCost.h"
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Module.h"
@@ -522,7 +523,13 @@
                                   InlineHistoryID, InsertLifetime, DL))
           continue;
         ++NumInlined;
-        
+
+        // Report the inline decision.
+        DiagnosticInfoOptimizationReport Diag(
+            DEBUG_TYPE, *Caller, CS.getInstruction()->getDebugLoc(),
+            Twine(Callee->getName() + " inlined into " + Caller->getName()));
+        Caller->getContext().diagnose(Diag);
+
         // If inlining this function gave us any new call sites, throw them
         // onto our worklist to process.  They are useful inline candidates.
         if (!InlineInfo.InlinedCalls.empty()) {