Index: lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1251,6 +1251,34 @@
   return nullptr;
 }
 
+static Instruction *simplifyCosSin(IntrinsicInst &II, InstCombiner &IC) {
+  Value *SrcSrc;
+  Value *Src = II.getArgOperand(0);
+  if (II.getIntrinsicID() == Intrinsic::cos ||
+      II.getIntrinsicID() == Intrinsic::amdgcn_cos) {
+    if (match(Src, m_FNeg(m_Value(SrcSrc))) ||
+        match(Src, m_Intrinsic<Intrinsic::fabs>(m_Value(SrcSrc)))) {
+      // cos(-x) -> cos(x)
+      // cos(fabs(x)) -> cos(x)
+      II.setArgOperand(0, SrcSrc);
+      return &II;
+    }
+  }
+
+  if (!II.isFast())
+    return nullptr;
+
+  if (CallInst *CallI = dyn_cast<CallInst>(Src)) {
+    StringRef Name = CallI->getCalledFunction()->getName();
+    if ((II.getIntrinsicID() == Intrinsic::cos && Name == "acos") ||
+        (II.getIntrinsicID() == Intrinsic::sin && Name == "asin")) {
+      return IC.replaceInstUsesWith(II, CallI->getArgOperand(0));
+    }
+  }
+
+  return nullptr;
+}
+
 static bool maskIsAllOneOrUndef(Value *Mask) {
   auto *ConstMask = dyn_cast<Constant>(Mask);
   if (!ConstMask)
@@ -2101,19 +2129,13 @@
     break;
   }
   case Intrinsic::cos:
-  case Intrinsic::amdgcn_cos: {
-    Value *SrcSrc;
-    Value *Src = II->getArgOperand(0);
-    if (match(Src, m_FNeg(m_Value(SrcSrc))) ||
-        match(Src, m_Intrinsic<Intrinsic::fabs>(m_Value(SrcSrc)))) {
-      // cos(-x) -> cos(x)
-      // cos(fabs(x)) -> cos(x)
-      II->setArgOperand(0, SrcSrc);
-      return II;
-    }
-
+  case Intrinsic::amdgcn_cos:
+  case Intrinsic::sin:
+  case Intrinsic::amdgcn_sin:
+    if (Instruction *I = simplifyCosSin(*II, *this))
+      return I;
     break;
-  }
+
   case Intrinsic::ppc_altivec_lvx:
   case Intrinsic::ppc_altivec_lvxl:
     // Turn PPC lvx -> load if the pointer is known aligned.
Index: test/Transforms/InstCombine/cos-intrinsic.ll
===================================================================
--- test/Transforms/InstCombine/cos-intrinsic.ll
+++ test/Transforms/InstCombine/cos-intrinsic.ll
@@ -8,6 +8,8 @@
 declare float @llvm.fabs.f32(float %Val)
 declare <2 x float> @llvm.fabs.v2f32(<2 x float> %Val)
 
+declare double @acos(double %Val)
+
 ; Function Attrs: nounwind readnone
 define double @test1() {
 ; CHECK-LABEL: define double @test1(
@@ -79,3 +81,21 @@
   %cos = call <2 x float> @llvm.cos.v2f32(<2 x float> %x.fabs.fneg)
   ret <2 x float> %cos
 }
+
+; CHECK-LABEL: @cos_acos(
+; CHECK-NEXT: %call = call double @acos(double %a)
+; CHECK-NEXT: %1 = call double @llvm.cos.f64(double %call)
+; CHECK-NEXT: ret double %1
+define double @cos_acos(double %a) {
+  %call = call double @acos(double %a)
+  %1 = call double @llvm.cos.f64(double %call)
+  ret double %1
+}
+
+; CHECK-LABEL: @cos_acos_fast(
+; CHECK-NEXT: ret double %a
+define double @cos_acos_fast(double %a) {
+  %call = call fast double @acos(double %a)
+  %1 = call fast double @llvm.cos.f64(double %call)
+  ret double %1
+}
Index: test/Transforms/InstCombine/sin-intrinsic.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/sin-intrinsic.ll
@@ -0,0 +1,22 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+declare double @llvm.sin.f64(double)
+declare double @asin(double)
+
+; CHECK-LABEL: @sin_asin(
+; CHECK-NEXT: %call = call double @asin(double %a)
+; CHECK-NEXT: %1 = call double @llvm.sin.f64(double %call)
+; CHECK-NEXT: ret double %1
+define double @sin_asin(double %a) {
+  %call = call double @asin(double %a)
+  %1 = call double @llvm.sin.f64(double %call)
+  ret double %1
+}
+
+; CHECK-LABEL: @sin_asin_fast(
+; CHECK-NEXT: ret double %a
+define double @sin_asin_fast(double %a) {
+  %call = call fast double @asin(double %a)
+  %1 = call fast double @llvm.sin.f64(double %call)
+  ret double %1
+}