Index: lib/Analysis/ConstantFolding.cpp
===================================================================
--- lib/Analysis/ConstantFolding.cpp
+++ lib/Analysis/ConstantFolding.cpp
@@ -1236,6 +1236,9 @@
   case Intrinsic::sqrt:
   case Intrinsic::sin:
   case Intrinsic::cos:
+  case Intrinsic::trunc:
+  case Intrinsic::rint:
+  case Intrinsic::nearbyint:
   case Intrinsic::pow:
   case Intrinsic::powi:
   case Intrinsic::bswap:
@@ -1456,6 +1459,12 @@
           return ConstantFoldFP(sin, V, Ty);
         case Intrinsic::cos:
           return ConstantFoldFP(cos, V, Ty);
+        case Intrinsic::trunc:
+          return ConstantFoldFP(trunc, V, Ty);
+        case Intrinsic::rint:
+          return ConstantFoldFP(rint, V, Ty);
+        case Intrinsic::nearbyint:
+          return ConstantFoldFP(nearbyint, V, Ty);
       }
 
       if (!TLI)
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.trunc.f64(double %Val) nounwind readonly
+declare double @llvm.rint.f64(double %Val) nounwind readonly
+declare double @llvm.nearbyint.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 @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
+}
+
+define void @rint(double *%P) {
+entry:
+  %B = tail call double @llvm.rint.f64(double 1.5) nounwind
+  store volatile double %B, double* %P
+  %C = tail call double @llvm.rint.f64(double -1.5) nounwind
+  store volatile double %C, double* %P
+  ret void
+; CHECK-LABEL: @rint(
+; CHECK: store volatile double 2.000000e+00, double* %P, align 8
+; CHECK: store volatile double -2.000000e+00, double* %P, align 8
+}
+
+define void @nearbyint(double *%P) {
+entry:
+  %B = tail call double @llvm.nearbyint.f64(double 1.5) nounwind
+  store volatile double %B, double* %P
+  %C = tail call double @llvm.nearbyint.f64(double -1.5) nounwind
+  store volatile double %C, double* %P
+  ret void
+; CHECK-LABEL: @nearbyint(
+; CHECK: store volatile double 2.000000e+00, double* %P, align 8
+; CHECK: store volatile double -2.000000e+00, double* %P, align 8
+}