Index: include/llvm/Analysis/TargetLibraryInfo.h
===================================================================
--- include/llvm/Analysis/TargetLibraryInfo.h
+++ include/llvm/Analysis/TargetLibraryInfo.h
@@ -11,6 +11,7 @@
 #define LLVM_ANALYSIS_TARGETLIBRARYINFO_H
 
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/IR/Function.h"
@@ -18,6 +19,14 @@
 #include "llvm/Pass.h"
 
 namespace llvm {
+/// VecDesc - Describes a possible vectorization of a function.
+/// Function 'VectorFnName' is equivalent to 'ScalarFnName' vectorized
+/// by a factor 'VectorizationFactor'.
+struct VecDesc {
+  const char *ScalarFnName;
+  const char *VectorFnName;
+  unsigned VectorizationFactor;
+};
 class PreservedAnalyses;
 
   namespace LibFunc {
@@ -722,6 +731,12 @@
     return static_cast<AvailabilityState>((AvailableArray[F/4] >> 2*(F&3)) & 3);
   }
 
+  /// Vectorization descriptors - sorted by ScalarFnName.
+  std::vector<VecDesc> VectorDescs;
+  /// Scalarization descriptors - same content as VectorDescs but sorted based
+  /// on VectorFnName rather than ScalarFnName.
+  std::vector<VecDesc> ScalarDescs;
+
 public:
   TargetLibraryInfoImpl();
   explicit TargetLibraryInfoImpl(const Triple &T);
@@ -764,6 +779,37 @@
   ///
   /// This can be used for options like -fno-builtin.
   void disableAllFunctions();
+
+  /// addVectorizableFunctions - Add a set of scalar -> vector mappings,
+  /// queryable via getVectorizedFunction and getScalarizedFunction.
+  void addVectorizableFunctions(ArrayRef<VecDesc> Fns);
+
+  /// isFunctionVectorizable - Return true if the function F has a
+  /// vector equivalent with vectorization factor VF.
+  bool isFunctionVectorizable(StringRef F, unsigned VF) const {
+    return !getVectorizedFunction(F, VF).empty();
+  }
+
+  /// isFunctionVectorizable - Return true if the function F has a
+  /// vector equivalent with any vectorization factor.
+  bool isFunctionVectorizable(StringRef F) const;
+
+  /// getVectorizedFunction - Return the name of the equivalent of
+  /// F, vectorized with factor VF. If no such mapping exists,
+  /// return the empty string.
+  StringRef getVectorizedFunction(StringRef F, unsigned VF) const;
+
+  /// isFunctionScalarizable - Return true if the function F has a
+  /// scalar equivalent, and set VF to be the vectorization factor.
+  bool isFunctionScalarizable(StringRef F, unsigned &VF) const {
+    return !getScalarizedFunction(F, VF).empty();
+  }
+
+  /// getScalarizedFunction - Return the name of the equivalent of
+  /// F, scalarized. If no such mapping exists, return the empty string.
+  ///
+  /// Set VF to the vectorization factor.
+  StringRef getScalarizedFunction(StringRef F, unsigned &VF) const;
 };
 
 /// \brief Provides information about what library functions are available for
@@ -804,6 +850,15 @@
   bool has(LibFunc::Func F) const {
     return Impl->getState(F) != TargetLibraryInfoImpl::Unavailable;
   }
+  bool isFunctionVectorizable(StringRef F, unsigned VF) const {
+    return Impl->isFunctionVectorizable(F, VF);
+  };
+  bool isFunctionVectorizable(StringRef F) const {
+    return Impl->isFunctionVectorizable(F);
+  };
+  StringRef getVectorizedFunction(StringRef F, unsigned VF) const {
+    return Impl->getVectorizedFunction(F, VF);
+  };
 
   /// \brief Tests if the function is both available and a candidate for
   /// optimized code generation.
Index: lib/Analysis/TargetLibraryInfo.cpp
===================================================================
--- lib/Analysis/TargetLibraryInfo.cpp
+++ lib/Analysis/TargetLibraryInfo.cpp
@@ -693,12 +693,16 @@
 TargetLibraryInfoImpl::TargetLibraryInfoImpl(const TargetLibraryInfoImpl &TLI)
     : CustomNames(TLI.CustomNames) {
   memcpy(AvailableArray, TLI.AvailableArray, sizeof(AvailableArray));
+  VectorDescs = TLI.VectorDescs;
+  ScalarDescs = TLI.ScalarDescs;
 }
 
 TargetLibraryInfoImpl::TargetLibraryInfoImpl(TargetLibraryInfoImpl &&TLI)
     : CustomNames(std::move(TLI.CustomNames)) {
   std::move(std::begin(TLI.AvailableArray), std::end(TLI.AvailableArray),
             AvailableArray);
+  VectorDescs = TLI.VectorDescs;
+  ScalarDescs = TLI.ScalarDescs;
 }
 
 TargetLibraryInfoImpl &TargetLibraryInfoImpl::operator=(const TargetLibraryInfoImpl &TLI) {
@@ -751,6 +755,72 @@
   memset(AvailableArray, 0, sizeof(AvailableArray));
 }
 
+static bool compareByScalarFnName(const VecDesc &LHS, const VecDesc &RHS) {
+  return std::strncmp(LHS.ScalarFnName, RHS.ScalarFnName,
+                      std::strlen(RHS.ScalarFnName)) < 0;
+}
+
+static bool compareByVectorFnName(const VecDesc &LHS, const VecDesc &RHS) {
+  return std::strncmp(LHS.VectorFnName, RHS.VectorFnName,
+                      std::strlen(RHS.VectorFnName)) < 0;
+}
+
+static bool compareWithScalarFnName(const VecDesc &LHS, StringRef S) {
+  return std::strncmp(LHS.ScalarFnName, S.data(), S.size()) < 0;
+}
+
+static bool compareWithVectorFnName(const VecDesc &LHS, StringRef S) {
+  return std::strncmp(LHS.VectorFnName, S.data(), S.size()) < 0;
+}
+
+void TargetLibraryInfoImpl::addVectorizableFunctions(ArrayRef<VecDesc> Fns) {
+  VectorDescs.insert(VectorDescs.end(), Fns.begin(), Fns.end());
+  std::sort(VectorDescs.begin(), VectorDescs.end(), compareByScalarFnName);
+
+  ScalarDescs.insert(ScalarDescs.end(), Fns.begin(), Fns.end());
+  std::sort(ScalarDescs.begin(), ScalarDescs.end(), compareByVectorFnName);
+}
+
+bool TargetLibraryInfoImpl::isFunctionVectorizable(StringRef funcName) const {
+  funcName = sanitizeFunctionName(funcName);
+  if (funcName.empty())
+    return false;
+
+  std::vector<VecDesc>::const_iterator I = std::lower_bound(
+      VectorDescs.begin(), VectorDescs.end(), funcName,
+      compareWithScalarFnName);
+  return I != VectorDescs.end() && StringRef(I->ScalarFnName) == funcName;
+}
+
+StringRef TargetLibraryInfoImpl::getVectorizedFunction(StringRef F,
+                                                       unsigned VF) const {
+  F = sanitizeFunctionName(F);
+  if (F.empty())
+    return F;
+  std::vector<VecDesc>::const_iterator I = std::lower_bound(
+      VectorDescs.begin(), VectorDescs.end(), F, compareWithScalarFnName);
+  while (I != VectorDescs.end() && StringRef(I->ScalarFnName) == F) {
+    if (I->VectorizationFactor == VF)
+      return I->VectorFnName;
+    ++I;
+  }
+  return StringRef();
+}
+
+StringRef TargetLibraryInfoImpl::getScalarizedFunction(StringRef F,
+                                                       unsigned &VF) const {
+  F = sanitizeFunctionName(F);
+  if (F.empty())
+    return F;
+
+  std::vector<VecDesc>::const_iterator I = std::lower_bound(
+      ScalarDescs.begin(), ScalarDescs.end(), F, compareWithVectorFnName);
+  if (I == VectorDescs.end() || StringRef(I->VectorFnName) != F)
+    return StringRef();
+  VF = I->VectorizationFactor;
+  return I->ScalarFnName;
+}
+
 TargetLibraryInfo TargetLibraryAnalysis::run(Module &M) {
   if (PresetInfoImpl)
     return TargetLibraryInfo(*PresetInfoImpl);