Index: llvm/include/llvm/Analysis/TargetLibraryInfo.def
===================================================================
--- llvm/include/llvm/Analysis/TargetLibraryInfo.def
+++ llvm/include/llvm/Analysis/TargetLibraryInfo.def
@@ -1119,6 +1119,15 @@
 /// char *realpath(const char *file_name, char *resolved_name);
 TLI_DEFINE_ENUM_INTERNAL(realpath)
 TLI_DEFINE_STRING_INTERNAL("realpath")
+/// double remainder(double x, double y);
+TLI_DEFINE_ENUM_INTERNAL(remainder)
+TLI_DEFINE_STRING_INTERNAL("remainder")
+/// float remainderf(float x, float y);
+TLI_DEFINE_ENUM_INTERNAL(remainderf)
+TLI_DEFINE_STRING_INTERNAL("remainderf")
+/// long double remainderl(long double x, long double y);
+TLI_DEFINE_ENUM_INTERNAL(remainderl)
+TLI_DEFINE_STRING_INTERNAL("remainderl")
 /// int remove(const char *path);
 TLI_DEFINE_ENUM_INTERNAL(remove)
 TLI_DEFINE_STRING_INTERNAL("remove")
Index: llvm/lib/Analysis/ConstantFolding.cpp
===================================================================
--- llvm/lib/Analysis/ConstantFolding.cpp
+++ llvm/lib/Analysis/ConstantFolding.cpp
@@ -1515,7 +1515,8 @@
   case 'p':
     return Name == "pow" || Name == "powf";
   case 'r':
-    return Name == "rint" || Name == "rintf" ||
+    return Name == "remainder" || Name == "remainderf" ||
+           Name == "rint" || Name == "rintf" ||
            Name == "round" || Name == "roundf";
   case 's':
     return Name == "sin" || Name == "sinf" ||
@@ -2095,6 +2096,14 @@
             return ConstantFP::get(Ty->getContext(), V);
         }
         break;
+      case LibFunc_remainder:
+      case LibFunc_remainderf:
+        if (TLI->has(Func)) {
+          APFloat V = Op1->getValueAPF();
+          if (APFloat::opStatus::opOK == V.remainder(Op2->getValueAPF()))
+            return ConstantFP::get(Ty->getContext(), V);
+        }
+        break;
       case LibFunc_atan2:
       case LibFunc_atan2f:
       case LibFunc_atan2_finite:
@@ -2624,6 +2633,9 @@
       case LibFunc_fmodl:
       case LibFunc_fmod:
       case LibFunc_fmodf:
+      case LibFunc_remainderl:
+      case LibFunc_remainder:
+      case LibFunc_remainderf:
         return Op0.isNaN() || Op1.isNaN() ||
                (!Op0.isInfinity() && !Op1.isZero());
 
Index: llvm/lib/Analysis/TargetLibraryInfo.cpp
===================================================================
--- llvm/lib/Analysis/TargetLibraryInfo.cpp
+++ llvm/lib/Analysis/TargetLibraryInfo.cpp
@@ -209,6 +209,7 @@
       TLI.setUnavailable(LibFunc_logf);
       TLI.setUnavailable(LibFunc_modff);
       TLI.setUnavailable(LibFunc_powf);
+      TLI.setUnavailable(LibFunc_remainderf);
       TLI.setUnavailable(LibFunc_sinf);
       TLI.setUnavailable(LibFunc_sinhf);
       TLI.setUnavailable(LibFunc_sqrtf);
@@ -238,6 +239,7 @@
     TLI.setUnavailable(LibFunc_logl);
     TLI.setUnavailable(LibFunc_modfl);
     TLI.setUnavailable(LibFunc_powl);
+    TLI.setUnavailable(LibFunc_remainderl);
     TLI.setUnavailable(LibFunc_sinl);
     TLI.setUnavailable(LibFunc_sinhl);
     TLI.setUnavailable(LibFunc_sqrtl);
@@ -1375,6 +1377,9 @@
   case LibFunc_fmod:
   case LibFunc_fmodf:
   case LibFunc_fmodl:
+  case LibFunc_remainder:
+  case LibFunc_remainderf:
+  case LibFunc_remainderl:
   case LibFunc_copysign:
   case LibFunc_copysignf:
   case LibFunc_copysignl:
Index: llvm/test/Analysis/ConstantFolding/math-2.ll
===================================================================
--- llvm/test/Analysis/ConstantFolding/math-2.ll
+++ llvm/test/Analysis/ConstantFolding/math-2.ll
@@ -20,6 +20,15 @@
   ret float %res
 }
 
+declare float @remainderf(float, float)
+define float @f_remainderf() {
+; CHECK-LABEL: @f_remainderf(
+; CHECK-NEXT:    ret float 1.000000e+00
+;
+  %res = tail call fast float @remainderf(float 1.0, float 2.0)
+  ret float %res
+}
+
 declare double @pow(double, double)
 define double @f_pow() {
 ; CHECK-LABEL: @f_pow(