Index: lib/Analysis/ConstantFolding.cpp
===================================================================
--- lib/Analysis/ConstantFolding.cpp
+++ lib/Analysis/ConstantFolding.cpp
@@ -1236,6 +1236,7 @@
   case Intrinsic::sqrt:
   case Intrinsic::sin:
   case Intrinsic::cos:
+  case Intrinsic::trunc:
   case Intrinsic::pow:
   case Intrinsic::powi:
   case Intrinsic::bswap:
@@ -1422,6 +1423,24 @@
         return ConstantFP::get(Ty->getContext(), V);
       }
 
+      if (IntrinsicID == Intrinsic::floor) {
+        APFloat V = Op->getValueAPF();
+        V.roundToIntegral(APFloat::rmTowardNegative);
+        return ConstantFP::get(Ty->getContext(), V);
+      }
+
+      if (IntrinsicID == Intrinsic::ceil) {
+        APFloat V = Op->getValueAPF();
+        V.roundToIntegral(APFloat::rmTowardPositive);
+        return ConstantFP::get(Ty->getContext(), V);
+      }
+
+      if (IntrinsicID == Intrinsic::trunc) {
+        APFloat V = Op->getValueAPF();
+        V.roundToIntegral(APFloat::rmTowardZero);
+        return ConstantFP::get(Ty->getContext(), V);
+      }
+
       /// We only fold functions with finite arguments. Folding NaN and inf is
       /// likely to be aborted with an exception anyway, and some host libms
       /// have known errors raising exceptions.
@@ -1448,10 +1467,6 @@
           return ConstantFoldFP(exp, V, Ty);
         case Intrinsic::exp2:
           return ConstantFoldFP(exp2, V, Ty);
-        case Intrinsic::floor:
-          return ConstantFoldFP(floor, V, Ty);
-        case Intrinsic::ceil:
-          return ConstantFoldFP(ceil, V, Ty);
         case Intrinsic::sin:
           return ConstantFoldFP(sin, V, Ty);
         case Intrinsic::cos:
Index: test/Transforms/InstCombine/intrinsics.ll
===================================================================
--- test/Transforms/InstCombine/intrinsics.ll
+++ test/Transforms/InstCombine/intrinsics.ll
@@ -19,6 +19,9 @@
 declare i8 @llvm.ctlz.i8(i8, i1) nounwind readnone
 declare double @llvm.cos.f64(double %Val) nounwind readonly
 declare double @llvm.sin.f64(double %Val) nounwind readonly
+declare double @llvm.floor.f64(double %Val) nounwind readonly
+declare double @llvm.ceil.f64(double %Val) nounwind readonly
+declare double @llvm.trunc.f64(double %Val) nounwind readonly
 
 define i8 @uaddtest1(i8 %A, i8 %B) {
   %x = call %overflow.result @llvm.uadd.with.overflow.i8(i8 %A, i8 %B)
@@ -447,3 +450,39 @@
 ; CHECK-LABEL: @sin(
 ; CHECK: store volatile double 0.000000e+00, double* %P
 }
+
+define void @floor(double *%P) {
+entry:
+  %B = tail call double @llvm.floor.f64(double 1.5) nounwind
+  store volatile double %B, double* %P
+  %C = tail call double @llvm.floor.f64(double -1.5) nounwind
+  store volatile double %C, double* %P
+  ret void
+; CHECK-LABEL: @floor(
+; CHECK: store volatile double 1.000000e+00, double* %P, align 8
+; CHECK: store volatile double -2.000000e+00, double* %P, align 8
+}
+
+define void @ceil(double *%P) {
+entry:
+  %B = tail call double @llvm.ceil.f64(double 1.5) nounwind
+  store volatile double %B, double* %P
+  %C = tail call double @llvm.ceil.f64(double -1.5) nounwind
+  store volatile double %C, double* %P
+  ret void
+; CHECK-LABEL: @ceil(
+; CHECK: store volatile double 2.000000e+00, double* %P, align 8
+; CHECK: store volatile double -1.000000e+00, double* %P, align 8
+}
+
+define void @trunc(double *%P) {
+entry:
+  %B = tail call double @llvm.trunc.f64(double 1.5) nounwind
+  store volatile double %B, double* %P
+  %C = tail call double @llvm.trunc.f64(double -1.5) nounwind
+  store volatile double %C, double* %P
+  ret void
+; CHECK-LABEL: @trunc(
+; CHECK: store volatile double 1.000000e+00, double* %P, align 8
+; CHECK: store volatile double -1.000000e+00, double* %P, align 8
+}