Index: include/llvm/Analysis/InlineCost.h
===================================================================
--- include/llvm/Analysis/InlineCost.h
+++ include/llvm/Analysis/InlineCost.h
@@ -74,8 +74,15 @@
   /// The adjusted threshold against which this cost was computed.
   const int Threshold;
 
+  /// Must be set for Always and Never instances.
+  const char* Reason = nullptr;
+
   // Trivial constructor, interesting logic in the factory functions below.
-  InlineCost(int Cost, int Threshold) : Cost(Cost), Threshold(Threshold) {}
+  InlineCost(int Cost, int Threshold, const char* Reason = nullptr) :
+      Cost(Cost), Threshold(Threshold), Reason(Reason) {
+    assert((isVariable() || Reason) &&
+           "Reason must be provided for Never or Always");
+  }
 
 public:
   static InlineCost get(int Cost, int Threshold) {
@@ -83,11 +90,11 @@
     assert(Cost < NeverInlineCost && "Cost crosses sentinel value");
     return InlineCost(Cost, Threshold);
   }
-  static InlineCost getAlways() {
-    return InlineCost(AlwaysInlineCost, 0);
+  static InlineCost getAlways(const char* Reason) {
+    return InlineCost(AlwaysInlineCost, 0, Reason);
   }
-  static InlineCost getNever() {
-    return InlineCost(NeverInlineCost, 0);
+  static InlineCost getNever(const char* Reason) {
+    return InlineCost(NeverInlineCost, 0, Reason);
   }
 
   /// Test whether the inline cost is low enough for inlining.
@@ -112,6 +119,13 @@
     return Threshold;
   }
 
+  /// Get the reason of Always or Never.
+  const char* getReason() const {
+    assert((Reason || isVariable()) &&
+           "InlineCost reason must be set for Always or Never");
+    return Reason;
+  }
+
   /// Get the cost delta from the threshold for inlining.
   /// Only valid if the cost is of the variable kind. Returns a negative
   /// value if the cost is too high to inline.
Index: include/llvm/IR/DiagnosticInfo.h
===================================================================
--- include/llvm/IR/DiagnosticInfo.h
+++ include/llvm/IR/DiagnosticInfo.h
@@ -414,6 +414,7 @@
     Argument(StringRef Key, const Value *V);
     Argument(StringRef Key, const Type *T);
     Argument(StringRef Key, StringRef S);
+    Argument(StringRef Key, const char* S) : Argument(Key, StringRef(S)) {};
     Argument(StringRef Key, int N);
     Argument(StringRef Key, float N);
     Argument(StringRef Key, long N);
Index: include/llvm/Transforms/Utils/Cloning.h
===================================================================
--- include/llvm/Transforms/Utils/Cloning.h
+++ include/llvm/Transforms/Utils/Cloning.h
@@ -213,6 +213,17 @@
   }
 };
 
+/// InlineResult is basically true or false. For false results the message
+/// describes a reason why it is decided to not inline.
+struct InlineResult {
+  const char* message = nullptr;
+  InlineResult(bool result, const char* message = nullptr)
+    : message(result ? nullptr : (message ? message : "cost > threshold")) {}
+  InlineResult(const char* message = nullptr) : message(message) {}
+  operator bool() const { return !message;}
+  operator const char*() const { return message; }
+};
+
 /// InlineFunction - This function inlines the called function into the basic
 /// block of the caller.  This returns false if it is not possible to inline
 /// this call.  The program is still in a well defined state if this occurs
@@ -232,13 +243,13 @@
 /// and all varargs at the callsite will be passed to any calls to
 /// ForwardVarArgsTo. The caller of InlineFunction has to make sure any varargs
 /// are only used by ForwardVarArgsTo.
-bool InlineFunction(CallInst *C, InlineFunctionInfo &IFI,
-                    AAResults *CalleeAAR = nullptr, bool InsertLifetime = true);
-bool InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
-                    AAResults *CalleeAAR = nullptr, bool InsertLifetime = true);
-bool InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
-                    AAResults *CalleeAAR = nullptr, bool InsertLifetime = true,
-                    Function *ForwardVarArgsTo = nullptr);
+InlineResult InlineFunction(CallInst *C, InlineFunctionInfo &IFI,
+                          AAResults *CalleeAAR = nullptr, bool InsertLifetime = true);
+InlineResult InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
+                           AAResults *CalleeAAR = nullptr, bool InsertLifetime = true);
+InlineResult InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
+                           AAResults *CalleeAAR = nullptr, bool InsertLifetime = true,
+                           Function *ForwardVarArgsTo = nullptr);
 
 /// Clones a loop \p OrigLoop.  Returns the loop and the blocks in \p
 /// Blocks.
Index: lib/Analysis/InlineCost.cpp
===================================================================
--- lib/Analysis/InlineCost.cpp
+++ lib/Analysis/InlineCost.cpp
@@ -37,6 +37,7 @@
 #include "llvm/IR/Operator.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/Cloning.h"
 
 using namespace llvm;
 
@@ -227,7 +228,7 @@
                                         BlockFrequencyInfo *CallerBFI);
 
   // Custom analysis routines.
-  bool analyzeBlock(BasicBlock *BB, SmallPtrSetImpl<const Value *> &EphValues);
+  InlineResult analyzeBlock(BasicBlock *BB, SmallPtrSetImpl<const Value *> &EphValues);
 
   // Disable several entry points to the visitor so we don't accidentally use
   // them by declaring but not defining them here.
@@ -290,7 +291,7 @@
         NumInstructionsSimplified(0), SROACostSavings(0),
         SROACostSavingsLost(0) {}
 
-  bool analyzeCall(CallSite CS);
+  InlineResult analyzeCall(CallSite CS);
 
   int getThreshold() { return Threshold; }
   int getCost() { return Cost; }
@@ -1541,8 +1542,8 @@
 /// aborts early if the threshold has been exceeded or an impossible to inline
 /// construct has been detected. It returns false if inlining is no longer
 /// viable, and true if inlining remains viable.
-bool CallAnalyzer::analyzeBlock(BasicBlock *BB,
-                                SmallPtrSetImpl<const Value *> &EphValues) {
+InlineResult CallAnalyzer::analyzeBlock(BasicBlock *BB,
+                                        SmallPtrSetImpl<const Value *> &EphValues) {
   for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
     // FIXME: Currently, the number of instructions in a function regardless of
     // our ability to simplify them during inline to constants or dead code,
@@ -1574,16 +1575,24 @@
 
     using namespace ore;
     // If the visit this instruction detected an uninlinable pattern, abort.
-    if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca ||
-        HasIndirectBr || HasUninlineableIntrinsic || UsesVarArgs) {
+    InlineResult IR;
+    if (IsRecursiveCall) IR = "recursive";
+    else if (ExposesReturnsTwice) IR = "exposes returns twice";
+    else if (HasDynamicAlloca) IR = "dynamic alloca";
+    else if (HasIndirectBr) IR = "indirect branch";
+    else if (HasUninlineableIntrinsic) IR = "uninlinable intrinsic";
+    else if (UsesVarArgs) IR = "varargs";
+    if (!IR) {
       if (ORE)
         ORE->emit([&]() {
           return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline",
                                           CandidateCS.getInstruction())
                  << NV("Callee", &F)
-                 << " has uninlinable pattern and cost is not fully computed";
+                 << " has uninlinable pattern ("
+                 << NV("InlineResult", IR.message)
+                 << ") and cost is not fully computed";
         });
-      return false;
+      return IR;
     }
 
     // If the caller is a recursive function then we don't want to inline
@@ -1591,15 +1600,16 @@
     // the caller stack usage dramatically.
     if (IsCallerRecursive &&
         AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller) {
+      InlineResult IR = "recursive and allocates too much stack space";
       if (ORE)
         ORE->emit([&]() {
           return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline",
                                           CandidateCS.getInstruction())
-                 << NV("Callee", &F)
-                 << " is recursive and allocates too much stack space. Cost is "
-                    "not fully computed";
+                 << NV("Callee", &F) << " is "
+                 << NV("InlineResult", IR.message)
+                 << ". Cost is not fully computed";
         });
-      return false;
+      return IR;
     }
 
     // Check if we've past the maximum possible threshold so we don't spin in
@@ -1695,7 +1705,7 @@
 /// factors and heuristics. If this method returns false but the computed cost
 /// is below the computed threshold, then inlining was forcibly disabled by
 /// some artifact of the routine.
-bool CallAnalyzer::analyzeCall(CallSite CS) {
+InlineResult CallAnalyzer::analyzeCall(CallSite CS) {
   ++NumCallsAnalyzed;
 
   // Perform some tweaks to the cost and threshold based on the direct
@@ -1730,7 +1740,7 @@
 
   // Check if we're done. This can happen due to bonuses and penalties.
   if (Cost >= Threshold && !ComputeFullInlineCost)
-    return false;
+    return "high cost";
 
   if (F.empty())
     return true;
@@ -1809,12 +1819,13 @@
     // site. If the blockaddress escapes the function, e.g., via a global
     // variable, inlining may lead to an invalid cross-function reference.
     if (BB->hasAddressTaken())
-      return false;
+      return "blockaddress";
 
     // Analyze the cost of this block. If we blow through the threshold, this
     // returns false, and we can bail on out.
-    if (!analyzeBlock(BB, EphValues))
-      return false;
+    InlineResult IR = analyzeBlock(BB, EphValues);
+    if (!IR)
+      return IR;
 
     TerminatorInst *TI = BB->getTerminator();
 
@@ -1867,7 +1878,7 @@
   // inlining this would cause the removal of the caller (so the instruction
   // is not actually duplicated, just moved).
   if (!OnlyOneCallAndLocalLinkage && ContainsNoDuplicateCall)
-    return false;
+    return "noduplicate";
 
   // We applied the maximum possible vector bonus at the beginning. Now,
   // subtract the excess bonus, if any, from the Threshold before
@@ -1961,7 +1972,7 @@
 
   // Cannot inline indirect calls.
   if (!Callee)
-    return llvm::InlineCost::getNever();
+    return llvm::InlineCost::getNever("indirect call");
 
   // Never inline calls with byval arguments that does not have the alloca
   // address space. Since byval arguments can be replaced with a copy to an
@@ -1973,54 +1984,60 @@
     if (CS.isByValArgument(I)) {
       PointerType *PTy = cast<PointerType>(CS.getArgument(I)->getType());
       if (PTy->getAddressSpace() != AllocaAS)
-        return llvm::InlineCost::getNever();
+        return llvm::InlineCost::getNever("byval arguments without alloca"
+                                          " address space");
     }
 
   // Calls to functions with always-inline attributes should be inlined
   // whenever possible.
   if (CS.hasFnAttr(Attribute::AlwaysInline)) {
     if (isInlineViable(*Callee))
-      return llvm::InlineCost::getAlways();
-    return llvm::InlineCost::getNever();
+      return llvm::InlineCost::getAlways("always inline attribute");
+    return llvm::InlineCost::getNever("inapplicable always inline attribute");
   }
 
   // Never inline functions with conflicting attributes (unless callee has
   // always-inline attribute).
   Function *Caller = CS.getCaller();
   if (!functionsHaveCompatibleAttributes(Caller, Callee, CalleeTTI))
-    return llvm::InlineCost::getNever();
+    return llvm::InlineCost::getNever("conflicting attributes");
 
   // Don't inline this call if the caller has the optnone attribute.
   if (Caller->hasFnAttribute(Attribute::OptimizeNone))
-    return llvm::InlineCost::getNever();
+    return llvm::InlineCost::getNever("optnone attribute");
 
   // Don't inline a function that treats null pointer as valid into a caller
   // that does not have this attribute.
   if (!Caller->nullPointerIsDefined() && Callee->nullPointerIsDefined())
-    return llvm::InlineCost::getNever();
+    return llvm::InlineCost::getNever("nullptr definitions incompatible");
+
+  // Don't inline functions which can be interposed at link-time.
+  if (Callee->isInterposable())
+    return llvm::InlineCost::getNever("interposable");
+
+  // Don't inline functions marked noinline.
+  if (Callee->hasFnAttribute(Attribute::NoInline))
+    return llvm::InlineCost::getNever("noinline function attribute");
+
+  // Don't inline call sites marked noinline.
+  if (CS.isNoInline())
+    return llvm::InlineCost::getNever("noinline call site attribute");
 
-  // Don't inline functions which can be interposed at link-time.  Don't inline
-  // functions marked noinline or call sites marked noinline.
-  // Note: inlining non-exact non-interposable functions is fine, since we know
-  // we have *a* correct implementation of the source level function.
-  if (Callee->isInterposable() || Callee->hasFnAttribute(Attribute::NoInline) ||
-      CS.isNoInline())
-    return llvm::InlineCost::getNever();
 
   LLVM_DEBUG(llvm::dbgs() << "      Analyzing call of " << Callee->getName()
                           << "... (caller:" << Caller->getName() << ")\n");
 
   CallAnalyzer CA(CalleeTTI, GetAssumptionCache, GetBFI, PSI, ORE, *Callee, CS,
                   Params);
-  bool ShouldInline = CA.analyzeCall(CS);
+  InlineResult ShouldInline = CA.analyzeCall(CS);
 
   LLVM_DEBUG(CA.dump());
 
   // Check if there was a reason to force inlining or no inlining.
   if (!ShouldInline && CA.getCost() < CA.getThreshold())
-    return InlineCost::getNever();
+    return InlineCost::getNever(ShouldInline.message);
   if (ShouldInline && CA.getCost() >= CA.getThreshold())
-    return InlineCost::getAlways();
+    return InlineCost::getAlways("empty function");
 
   return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
 }
Index: lib/Target/AMDGPU/AMDGPUInline.cpp
===================================================================
--- lib/Target/AMDGPU/AMDGPUInline.cpp
+++ lib/Target/AMDGPU/AMDGPUInline.cpp
@@ -174,18 +174,23 @@
   Function *Caller = CS.getCaller();
   TargetTransformInfo &TTI = TTIWP->getTTI(*Callee);
 
-  if (!Callee || Callee->isDeclaration() || CS.isNoInline() ||
-      !TTI.areInlineCompatible(Caller, Callee))
-    return llvm::InlineCost::getNever();
+  if (!Callee || Callee->isDeclaration())
+    return llvm::InlineCost::getNever("undefined callee");
+
+  if (CS.isNoInline())
+    return llvm::InlineCost::getNever("noinline");
+
+  if (!TTI.areInlineCompatible(Caller, Callee))
+    return llvm::InlineCost::getNever("incompatible");
 
   if (CS.hasFnAttr(Attribute::AlwaysInline)) {
     if (isInlineViable(*Callee))
-      return llvm::InlineCost::getAlways();
-    return llvm::InlineCost::getNever();
+      return llvm::InlineCost::getAlways("alwaysinline viable");
+    return llvm::InlineCost::getNever("alwaysinline unviable");
   }
 
   if (isWrapperOnlyCall(CS))
-    return llvm::InlineCost::getAlways();
+    return llvm::InlineCost::getAlways("wrapper-only call");
 
   InlineParams LocalParams = Params;
   LocalParams.DefaultThreshold = (int)getInlineThreshold(CS);
Index: lib/Transforms/IPO/AlwaysInliner.cpp
===================================================================
--- lib/Transforms/IPO/AlwaysInliner.cpp
+++ lib/Transforms/IPO/AlwaysInliner.cpp
@@ -150,7 +150,7 @@
   // declarations.
   if (Callee && !Callee->isDeclaration() &&
       CS.hasFnAttr(Attribute::AlwaysInline) && isInlineViable(*Callee))
-    return InlineCost::getAlways();
+    return InlineCost::getAlways("always inliner");
 
-  return InlineCost::getNever();
+  return InlineCost::getNever("always inliner");
 }
Index: lib/Transforms/IPO/Inliner.cpp
===================================================================
--- lib/Transforms/IPO/Inliner.cpp
+++ lib/Transforms/IPO/Inliner.cpp
@@ -275,8 +275,9 @@
 
   // Try to inline the function.  Get the list of static allocas that were
   // inlined.
-  if (!InlineFunction(CS, IFI, &AAR, InsertLifetime))
-    return false;
+  InlineResult IR = InlineFunction(CS, IFI, &AAR, InsertLifetime);
+  if (!IR)
+    return IR;
 
   if (InlinerFunctionImportStats != InlinerFunctionImportStatsOpts::No)
     ImportedFunctionsStats.recordInline(*Caller, *Callee);
@@ -286,7 +287,7 @@
   if (!DisableInlinedAllocaMerging)
     mergeInlinedArrayAllocas(Caller, IFI, InlinedArrayAllocas, InlineHistory);
 
-  return true;
+  return IR; // success
 }
 
 /// Return true if inlining of CS can block the caller from being
@@ -365,6 +366,42 @@
   return false;
 }
 
+static std::string inlineCostStr(InlineCost& IC) {
+  std::string Message;
+
+  if (IC.isAlways()) {
+    Message += "cost=always";
+  } else if (IC.isNever()) {
+    Message += "cost=never";
+  } else {
+    Message += "cost=";
+    Message += std::to_string(IC.getCost());
+    Message += " (threshold=";
+    Message += std::to_string(IC.getThreshold());
+    Message += ")";
+  }
+  if (const char* Reason = IC.getReason())
+    Message += std::string(": ") + Reason;
+
+  return Message;
+}
+
+template <class RemarkT>
+RemarkT& operator<< (RemarkT &&R, const InlineCost& IC) {
+  using namespace ore;
+  if (IC.isAlways()) {
+    R << "cost=always";
+  } else if (IC.isNever()) {
+    R << "cost=never";
+  } else {
+    R << "cost=" << ore::NV("Cost", IC.getCost())
+      << " (threshold=" << ore::NV("Threshold", IC.getThreshold()) << ")";
+  }
+  if (const char* Reason = IC.getReason())
+    R << std::string(": ") << ore::NV("Reason", Reason);
+  return R;
+}
+
 /// Return the cost only if the inliner should attempt to inline at the given
 /// CallSite. If we return the cost, we will emit an optimisation remark later
 /// using that cost, so we won't do so from this function.
@@ -379,35 +416,33 @@
   Function *Caller = CS.getCaller();
 
   if (IC.isAlways()) {
-    LLVM_DEBUG(dbgs() << "    Inlining: cost=always"
+    LLVM_DEBUG(dbgs() << "    Inlining: " << inlineCostStr(IC)
                       << ", Call: " << *CS.getInstruction() << "\n");
     return IC;
   }
 
   if (IC.isNever()) {
-    LLVM_DEBUG(dbgs() << "    NOT Inlining: cost=never"
+    LLVM_DEBUG(dbgs() << "    NOT Inlining: " << inlineCostStr(IC)
                       << ", Call: " << *CS.getInstruction() << "\n");
     ORE.emit([&]() {
       return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline", Call)
              << NV("Callee", Callee) << " not inlined into "
              << NV("Caller", Caller)
-             << " because it should never be inlined (cost=never)";
+             << " because it should never be inlined " << IC;
     });
-    return None;
+    return IC;
   }
 
   if (!IC) {
-    LLVM_DEBUG(dbgs() << "    NOT Inlining: cost=" << IC.getCost()
-                      << ", thres=" << IC.getThreshold()
+    LLVM_DEBUG(dbgs() << "    NOT Inlining: " << inlineCostStr(IC)
                       << ", Call: " << *CS.getInstruction() << "\n");
     ORE.emit([&]() {
       return OptimizationRemarkMissed(DEBUG_TYPE, "TooCostly", Call)
              << NV("Callee", Callee) << " not inlined into "
-             << NV("Caller", Caller) << " because too costly to inline (cost="
-             << NV("Cost", IC.getCost())
-             << ", threshold=" << NV("Threshold", IC.getThreshold()) << ")";
+             << NV("Caller", Caller) << " because too costly to inline ("
+             << IC << ")";
     });
-    return None;
+    return IC;
   }
 
   int TotalSecondaryCost = 0;
@@ -428,8 +463,7 @@
     return None;
   }
 
-  LLVM_DEBUG(dbgs() << "    Inlining: cost=" << IC.getCost()
-                    << ", thres=" << IC.getThreshold()
+  LLVM_DEBUG(dbgs() << "    Inlining: " << inlineCostStr(IC)
                     << ", Call: " << *CS.getInstruction() << '\n');
   return IC;
 }
@@ -461,6 +495,18 @@
   return inlineCalls(SCC);
 }
 
+static void emit_inlined_into(OptimizationRemarkEmitter &ORE, DebugLoc &DLoc,
+                              const BasicBlock *Block, const Function &Callee,
+                              const Function &Caller,const InlineCost& IC) {
+  ORE.emit([&]() {
+    bool AlwaysInline = IC.isAlways();
+    StringRef RemarkName = AlwaysInline ? "AlwaysInline" : "Inlined";
+    return OptimizationRemark(DEBUG_TYPE, RemarkName, DLoc, Block)
+         << ore::NV("Callee", &Callee) << " inlined into "
+         << ore::NV("Caller", &Caller) << " with " << IC;
+  });
+}
+
 static bool
 inlineCallsImpl(CallGraphSCC &SCC, CallGraph &CG,
                 std::function<AssumptionCache &(Function &)> GetAssumptionCache,
@@ -585,8 +631,9 @@
       Optional<InlineCost> OIC = shouldInline(CS, GetInlineCost, ORE);
       // If the policy determines that we should inline this function,
       // delete the call instead.
-      if (!OIC)
+      if (!OIC || !*OIC) {
         continue;
+      }
 
       // If this call site is dead and it is to a readonly function, we should
       // just delete the call instead of trying to inline it, regardless of
@@ -606,34 +653,24 @@
         // Attempt to inline the function.
         using namespace ore;
 
-        if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas,
-                                  InlineHistoryID, InsertLifetime, AARGetter,
-                                  ImportedFunctionsStats)) {
+        InlineResult IR = InlineCallIfPossible(CS, InlineInfo,
+                                               InlinedArrayAllocas,
+                                               InlineHistoryID, InsertLifetime,
+                                               AARGetter,
+                                               ImportedFunctionsStats);
+        if (!IR) {
           ORE.emit([&]() {
             return OptimizationRemarkMissed(DEBUG_TYPE, "NotInlined", DLoc,
                                             Block)
                    << NV("Callee", Callee) << " will not be inlined into "
-                   << NV("Caller", Caller);
+                   << NV("Caller", Caller) << ": "
+                   << NV("Reason", IR.message);
           });
           continue;
         }
         ++NumInlined;
 
-        ORE.emit([&]() {
-          bool AlwaysInline = OIC->isAlways();
-          StringRef RemarkName = AlwaysInline ? "AlwaysInline" : "Inlined";
-          OptimizationRemark R(DEBUG_TYPE, RemarkName, DLoc, Block);
-          R << NV("Callee", Callee) << " inlined into ";
-          R << NV("Caller", Caller);
-          if (AlwaysInline)
-            R << " with cost=always";
-          else {
-            R << " with cost=" << NV("Cost", OIC->getCost());
-            R << " (threshold=" << NV("Threshold", OIC->getThreshold());
-            R << ")";
-          }
-          return R;
-        });
+        emit_inlined_into(ORE, DLoc, Block, *Callee, *Caller, *OIC);
 
         // If inlining this function gave us any new call sites, throw them
         // onto our worklist to process.  They are useful inline candidates.
@@ -658,7 +695,7 @@
           // could invalidate the CGSCC iterator.
           CG[Callee]->getNumReferences() == 0) {
         LLVM_DEBUG(dbgs() << "    -> Deleting dead function: "
-                          << Callee->getName() << "\n");
+                << Callee->getName() << "\n");
         CallGraphNode *CalleeNode = CG[Callee];
 
         // Remove any call graph edges from the callee to its callees.
@@ -713,7 +750,7 @@
 
 /// Remove dead functions that are not included in DNR (Do Not Remove) list.
 bool LegacyInlinerBase::removeDeadFunctions(CallGraph &CG,
-                                            bool AlwaysInlineOnly) {
+        bool AlwaysInlineOnly) {
   SmallVector<CallGraphNode *, 16> FunctionsToRemove;
   SmallVector<Function *, 16> DeadFunctionsInComdats;
 
@@ -784,8 +821,8 @@
   // in.
   array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end());
   FunctionsToRemove.erase(
-      std::unique(FunctionsToRemove.begin(), FunctionsToRemove.end()),
-      FunctionsToRemove.end());
+          std::unique(FunctionsToRemove.begin(), FunctionsToRemove.end()),
+          FunctionsToRemove.end());
   for (CallGraphNode *CGN : FunctionsToRemove) {
     delete CG.removeFunctionFromModule(CGN);
     ++NumDeleted;
@@ -846,13 +883,13 @@
   SmallVector<std::pair<CallSite, int>, 16> Calls;
 
   FunctionAnalysisManager &FAM =
-      AM.getResult<FunctionAnalysisManagerCGSCCProxy>(InitialC, CG)
+          AM.getResult<FunctionAnalysisManagerCGSCCProxy>(InitialC, CG)
           .getManager();
 
   // Populate the initial list of calls in this SCC.
   for (auto &N : InitialC) {
     auto &ORE =
-        FAM.getResult<OptimizationRemarkEmitterAnalysis>(N.getFunction());
+            FAM.getResult<OptimizationRemarkEmitterAnalysis>(N.getFunction());
     // We want to generally process call sites top-down in order for
     // simplifications stemming from replacing the call with the returned value
     // after inlining to be visible to subsequent inlining decisions.
@@ -971,7 +1008,7 @@
 
       Optional<InlineCost> OIC = shouldInline(CS, GetInlineCost, ORE);
       // Check whether we want to inline this callsite.
-      if (!OIC)
+      if (!OIC || !*OIC)
         continue;
 
       // Setup the data structure used to plumb customization into the
@@ -987,32 +1024,20 @@
 
       using namespace ore;
 
-      if (!InlineFunction(CS, IFI)) {
+      InlineResult IR = InlineFunction(CS, IFI);
+      if (!IR) {
         ORE.emit([&]() {
           return OptimizationRemarkMissed(DEBUG_TYPE, "NotInlined", DLoc, Block)
                  << NV("Callee", &Callee) << " will not be inlined into "
-                 << NV("Caller", &F);
+                 << NV("Caller", &F) << ": "
+                 << NV("Reason", IR.message);
         });
         continue;
       }
       DidInline = true;
       InlinedCallees.insert(&Callee);
 
-      ORE.emit([&]() {
-        bool AlwaysInline = OIC->isAlways();
-        StringRef RemarkName = AlwaysInline ? "AlwaysInline" : "Inlined";
-        OptimizationRemark R(DEBUG_TYPE, RemarkName, DLoc, Block);
-        R << NV("Callee", &Callee) << " inlined into ";
-        R << NV("Caller", &F);
-        if (AlwaysInline)
-          R << " with cost=always";
-        else {
-          R << " with cost=" << NV("Cost", OIC->getCost());
-          R << " (threshold=" << NV("Threshold", OIC->getThreshold());
-          R << ")";
-        }
-        return R;
-      });
+      emit_inlined_into(ORE, DLoc, Block, Callee, F, *OIC);
 
       // Add any new callsites to defined functions to the worklist.
       if (!IFI.InlinedCallSites.empty()) {
Index: lib/Transforms/Utils/InlineFunction.cpp
===================================================================
--- lib/Transforms/Utils/InlineFunction.cpp
+++ lib/Transforms/Utils/InlineFunction.cpp
@@ -84,13 +84,15 @@
   cl::init(true), cl::Hidden,
   cl::desc("Convert align attributes to assumptions during inlining."));
 
-bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI,
-                          AAResults *CalleeAAR, bool InsertLifetime) {
+llvm::InlineResult llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI,
+                                        AAResults *CalleeAAR,
+                                        bool InsertLifetime) {
   return InlineFunction(CallSite(CI), IFI, CalleeAAR, InsertLifetime);
 }
 
-bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
-                          AAResults *CalleeAAR, bool InsertLifetime) {
+llvm::InlineResult llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
+                                        AAResults *CalleeAAR,
+                                        bool InsertLifetime) {
   return InlineFunction(CallSite(II), IFI, CalleeAAR, InsertLifetime);
 }
 
@@ -1491,7 +1493,7 @@
 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
 /// exists in the instruction stream.  Similarly this will inline a recursive
 /// function by one level.
-bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
+llvm::InlineResult llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
                           AAResults *CalleeAAR, bool InsertLifetime,
                           Function *ForwardVarArgsTo) {
   Instruction *TheCall = CS.getInstruction();
@@ -1504,7 +1506,7 @@
   Function *CalledFunc = CS.getCalledFunction();
   if (!CalledFunc ||               // Can't inline external function or indirect
       CalledFunc->isDeclaration()) // call!
-    return false;
+    return "external or indirect";
 
   // The inliner does not know how to inline through calls with operand bundles
   // in general ...
@@ -1518,7 +1520,7 @@
       if (Tag == LLVMContext::OB_funclet)
         continue;
 
-      return false;
+      return "unsupported operand bundle";
     }
   }
 
@@ -1537,7 +1539,7 @@
     if (!Caller->hasGC())
       Caller->setGC(CalledFunc->getGC());
     else if (CalledFunc->getGC() != Caller->getGC())
-      return false;
+      return "incompatible GC";
   }
 
   // Get the personality function from the callee if it contains a landing pad.
@@ -1561,7 +1563,7 @@
     // TODO: This isn't 100% true. Some personality functions are proper
     //       supersets of others and can be used in place of the other.
     else if (CalledPersonality != CallerPersonality)
-      return false;
+      return "incompatible personality";
   }
 
   // We need to figure out which funclet the callsite was in so that we may
@@ -1586,7 +1588,7 @@
             // for catchpads.
             for (const BasicBlock &CalledBB : *CalledFunc) {
               if (isa<CatchSwitchInst>(CalledBB.getFirstNonPHI()))
-                return false;
+                return "catch in cleanup funclet";
             }
           }
         } else if (isAsynchronousEHPersonality(Personality)) {
@@ -1594,7 +1596,7 @@
           // funclet in the callee.
           for (const BasicBlock &CalledBB : *CalledFunc) {
             if (CalledBB.isEHPad())
-              return false;
+              return "SEH in cleanup funclet";
           }
         }
       }
Index: test/LTO/Resolution/X86/diagnostic-handler-remarks-with-hotness.ll
===================================================================
--- test/LTO/Resolution/X86/diagnostic-handler-remarks-with-hotness.ll
+++ test/LTO/Resolution/X86/diagnostic-handler-remarks-with-hotness.ll
@@ -25,7 +25,8 @@
 ; YAML-NEXT:   - Callee:          tinkywinky
 ; YAML-NEXT:   - String:          ' inlined into '
 ; YAML-NEXT:   - Caller:          main
-; YAML-NEXT:   - String:          ' with cost='
+; YAML-NEXT:   - String:          ' with '
+; YAML-NEXT:   - String:          'cost='
 ; YAML-NEXT:   - Cost:            '-15000'
 ; YAML-NEXT:   - String:          ' (threshold='
 ; YAML-NEXT:   - Threshold:       '337'
Index: test/LTO/Resolution/X86/diagnostic-handler-remarks.ll
===================================================================
--- test/LTO/Resolution/X86/diagnostic-handler-remarks.ll
+++ test/LTO/Resolution/X86/diagnostic-handler-remarks.ll
@@ -26,7 +26,8 @@
 ; YAML-NEXT:   - Callee:          tinkywinky
 ; YAML-NEXT:   - String:          ' inlined into '
 ; YAML-NEXT:   - Caller:          main
-; YAML-NEXT:   - String:          ' with cost='
+; YAML-NEXT:   - String:          ' with '
+; YAML-NEXT:   - String:          'cost='
 ; YAML-NEXT:   - Cost:            '-15000'
 ; YAML-NEXT:   - String:          ' (threshold='
 ; YAML-NEXT:   - Threshold:       '337'
Index: test/LTO/X86/diagnostic-handler-remarks-with-hotness.ll
===================================================================
--- test/LTO/X86/diagnostic-handler-remarks-with-hotness.ll
+++ test/LTO/X86/diagnostic-handler-remarks-with-hotness.ll
@@ -17,7 +17,8 @@
 ; YAML-NEXT:   - Callee:          foo
 ; YAML-NEXT:   - String:          ' inlined into '
 ; YAML-NEXT:   - Caller:          main
-; YAML-NEXT:   - String:          ' with cost='
+; YAML-NEXT:   - String:          ' with '
+; YAML-NEXT:   - String:          'cost='
 ; YAML-NEXT:   - Cost:            '-15000'
 ; YAML-NEXT:   - String:          ' (threshold='
 ; YAML-NEXT:   - Threshold:       '337'
Index: test/LTO/X86/diagnostic-handler-remarks.ll
===================================================================
--- test/LTO/X86/diagnostic-handler-remarks.ll
+++ test/LTO/X86/diagnostic-handler-remarks.ll
@@ -53,7 +53,8 @@
 ; YAML-NEXT:   - Callee:          foo
 ; YAML-NEXT:   - String:          ' inlined into '
 ; YAML-NEXT:   - Caller:          main
-; YAML-NEXT:   - String:          ' with cost='
+; YAML-NEXT:   - String:          ' with '
+; YAML-NEXT:   - String:          'cost='
 ; YAML-NEXT:   - Cost:            '-15000'
 ; YAML-NEXT:   - String:          ' (threshold='
 ; YAML-NEXT:   - Threshold:       '337'
Index: test/ThinLTO/X86/diagnostic-handler-remarks-with-hotness.ll
===================================================================
--- test/ThinLTO/X86/diagnostic-handler-remarks-with-hotness.ll
+++ test/ThinLTO/X86/diagnostic-handler-remarks-with-hotness.ll
@@ -25,7 +25,8 @@
 ; YAML1-NEXT:   - Callee:          foo
 ; YAML1-NEXT:   - String:          ' inlined into '
 ; YAML1-NEXT:   - Caller:          main
-; YAML1-NEXT:   - String:          ' with cost='
+; YAML1-NEXT:   - String:          ' with '
+; YAML1-NEXT:   - String:          'cost='
 ; YAML1-NEXT:   - Cost:            '-30'
 ; YAML1-NEXT:   - String:          ' (threshold='
 ; YAML1-NEXT:   - Threshold:       '337'
@@ -43,7 +44,8 @@
 ; YAML2-NEXT:   - Callee:          bar
 ; YAML2-NEXT:   - String:          ' inlined into '
 ; YAML2-NEXT:   - Caller:          foo
-; YAML2-NEXT:   - String:          ' with cost='
+; YAML2-NEXT:   - String:          ' with '
+; YAML2-NEXT:   - String:          'cost='
 ; YAML2-NEXT:   - Cost:            '-30'
 ; YAML2-NEXT:   - String:          ' (threshold='
 ; YAML2-NEXT:   - Threshold:       '337'
Index: test/ThinLTO/X86/diagnostic-handler-remarks.ll
===================================================================
--- test/ThinLTO/X86/diagnostic-handler-remarks.ll
+++ test/ThinLTO/X86/diagnostic-handler-remarks.ll
@@ -22,7 +22,8 @@
 ; YAML1-NEXT:   - Callee:          foo
 ; YAML1-NEXT:   - String:          ' inlined into '
 ; YAML1-NEXT:   - Caller:          main
-; YAML1-NEXT:   - String:          ' with cost='
+; YAML1-NEXT:   - String:          ' with '
+; YAML1-NEXT:   - String:          'cost='
 ; YAML1-NEXT:   - Cost:            '-30'
 ; YAML1-NEXT:   - String:          ' (threshold='
 ; YAML1-NEXT:   - Threshold:       '337'
@@ -40,7 +41,8 @@
 ; YAML2-NEXT:   - Callee:          bar
 ; YAML2-NEXT:   - String:          ' inlined into '
 ; YAML2-NEXT:   - Caller:          foo
-; YAML2-NEXT:   - String:          ' with cost='
+; YAML2-NEXT:   - String:          ' with '
+; YAML2-NEXT:   - String:          'cost='
 ; YAML2-NEXT:   - Cost:            '-30'
 ; YAML2-NEXT:   - String:          ' (threshold='
 ; YAML2-NEXT:   - Threshold:       '337'
Index: test/Transforms/Inline/ARM/inline-fp.ll
===================================================================
--- test/Transforms/Inline/ARM/inline-fp.ll
+++ test/Transforms/Inline/ARM/inline-fp.ll
@@ -4,14 +4,14 @@
 ; Make sure that soft float implementations are calculated as being more expensive
 ; to the inliner.
 
-; NOFP-DAG: single not inlined into test_single because too costly to inline (cost=125, threshold=75)
-; NOFP-DAG: single not inlined into test_single because too costly to inline (cost=125, threshold=75)
+; NOFP-DAG: single not inlined into test_single because too costly to inline (cost=125 (threshold=75))
+; NOFP-DAG: single not inlined into test_single because too costly to inline (cost=125 (threshold=75))
 ; NOFP-DAG: single_cheap inlined into test_single_cheap with cost=-15 (threshold=75)
 ; NOFP-DAG: single_cheap inlined into test_single_cheap with cost=-15015 (threshold=75)
-; NOFP-DAG: double not inlined into test_double because too costly to inline (cost=125, threshold=75)
-; NOFP-DAG: double not inlined into test_double because too costly to inline (cost=125, threshold=75)
-; NOFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
-; NOFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
+; NOFP-DAG: double not inlined into test_double because too costly to inline (cost=125 (threshold=75))
+; NOFP-DAG: double not inlined into test_double because too costly to inline (cost=125 (threshold=75))
+; NOFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125 (threshold=75))
+; NOFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125 (threshold=75))
 
 ; FULLFP-DAG: single inlined into test_single with cost=0 (threshold=75)
 ; FULLFP-DAG: single inlined into test_single with cost=-15000 (threshold=75)
@@ -19,17 +19,17 @@
 ; FULLFP-DAG: single_cheap inlined into test_single_cheap with cost=-15015 (threshold=75)
 ; FULLFP-DAG: double inlined into test_double with cost=0 (threshold=75)
 ; FULLFP-DAG: double inlined into test_double with cost=-15000 (threshold=75)
-; FULLFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
-; FULLFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
+; FULLFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125 (threshold=75))
+; FULLFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125 (threshold=75))
 
 ; SINGLEFP-DAG: single inlined into test_single with cost=0 (threshold=75)
 ; SINGLEFP-DAG: single inlined into test_single with cost=-15000 (threshold=75)
 ; SINGLEFP-DAG: single_cheap inlined into test_single_cheap with cost=-15 (threshold=75)
 ; SINGLEFP-DAG: single_cheap inlined into test_single_cheap with cost=-15015 (threshold=75)
-; SINGLEFP-DAG: double not inlined into test_double because too costly to inline (cost=125, threshold=75)
-; SINGLEFP-DAG: double not inlined into test_double because too costly to inline (cost=125, threshold=75)
-; SINGLEFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
-; SINGLEFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
+; SINGLEFP-DAG: double not inlined into test_double because too costly to inline (cost=125 (threshold=75))
+; SINGLEFP-DAG: double not inlined into test_double because too costly to inline (cost=125 (threshold=75))
+; SINGLEFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125 (threshold=75))
+; SINGLEFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125 (threshold=75))
 
 define i32 @test_single(i32 %a, i8 %b, i32 %c, i8 %d) #0 {
   %call = call float @single(i32 %a, i8 zeroext %b)
Index: test/Transforms/Inline/optimization-remarks-passed-yaml.ll
===================================================================
--- test/Transforms/Inline/optimization-remarks-passed-yaml.ll
+++ test/Transforms/Inline/optimization-remarks-passed-yaml.ll
@@ -31,7 +31,8 @@
 ; YAML-NEXT:   - String: ' inlined into '
 ; YAML-NEXT:   - Caller: bar
 ; YAML-NEXT:     DebugLoc:        { File: /tmp/s.c, Line: 3, Column: 0 }
-; YAML-NEXT:   - String: ' with cost='
+; YAML-NEXT:   - String: ' with '
+; YAML-NEXT:   - String: 'cost='
 ; YAML-NEXT:   - Cost: '{{[0-9\-]+}}'
 ; YAML-NEXT:   - String: ' (threshold='
 ; YAML-NEXT:   - Threshold: '{{[0-9]+}}'
Index: test/Transforms/Inline/optimization-remarks-with-hotness.ll
===================================================================
--- test/Transforms/Inline/optimization-remarks-with-hotness.ll
+++ test/Transforms/Inline/optimization-remarks-with-hotness.ll
@@ -5,8 +5,8 @@
 ; RUN:     -pass-remarks-analysis=inline -pass-remarks-with-hotness -S 2>&1 \
 ; RUN:     | FileCheck %s
 
-; CHECK: foo inlined into bar with cost=always (hotness: 30)
-; CHECK: foz not inlined into bar because it should never be inlined (cost=never) (hotness: 30)
+; CHECK: foo inlined into bar with cost=always: always inline attribute (hotness: 30)
+; CHECK: foz not inlined into bar because it should never be inlined cost=never: noinline function attribute (hotness: 30)
 
 ; Function Attrs: alwaysinline nounwind uwtable
 define i32 @foo() #0 !prof !1 {
Index: test/Transforms/Inline/optimization-remarks.ll
===================================================================
--- test/Transforms/Inline/optimization-remarks.ll
+++ test/Transforms/Inline/optimization-remarks.ll
@@ -15,7 +15,7 @@
 ; HOTNESS: fox will not be inlined into bar because its definition is unavailable
 ; NO_HOTNESS-NOT: fox will not be inlined into bar because its definition is unavailable
 ; CHECK: foo inlined into bar with cost=always
-; CHECK: foz not inlined into bar because it should never be inlined (cost=never)
+; CHECK: foz not inlined into bar because it should never be inlined cost=never: noinline function attribute
 
 ; Function Attrs: alwaysinline nounwind uwtable
 define i32 @foo(i32 %x, i32 %y) #0 !prof !1 {
Index: test/tools/gold/X86/opt-remarks.ll
===================================================================
--- test/tools/gold/X86/opt-remarks.ll
+++ test/tools/gold/X86/opt-remarks.ll
@@ -34,7 +34,8 @@
 ; YAML-NEXT:   - Callee:          f
 ; YAML-NEXT:   - String:          ' inlined into '
 ; YAML-NEXT:   - Caller:          _start
-; YAML-NEXT:   - String:          ' with cost='
+; YAML-NEXT:   - String:          ' with '
+; YAML-NEXT:   - String:          'cost='
 ; YAML-NEXT:   - Cost:            '0'
 ; YAML-NEXT:   - String:          ' (threshold='
 ; YAML-NEXT:   - Threshold:       '337'
@@ -51,7 +52,8 @@
 ; YAML-HOT-NEXT:   - Callee:          f
 ; YAML-HOT-NEXT:   - String:          ' inlined into '
 ; YAML-HOT-NEXT:   - Caller:          _start
-; YAML-HOT-NEXT:   - String:          ' with cost='
+; YAML-HOT-NEXT:   - String:          ' with'
+; YAML-HOT-NEXT:   - String:          'cost='
 ; YAML-HOT-NEXT:   - Cost:            '0'
 ; YAML-HOT-NEXT:   - String:          ' (threshold='
 ; YAML-HOT-NEXT:   - Threshold:       '337'