Index: lib/Transforms/Utils/SimplifyLibCalls.cpp
===================================================================
--- lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -840,12 +840,8 @@
   if (!FillValue || FillValue->getZExtValue() != 0)
     return nullptr;
 
-  // TODO: We should handle the case where the malloc has more than one use.
-  // This is necessary to optimize common patterns such as when the result of
-  // the malloc is checked against null or when a memset intrinsic is used in
-  // place of a memset library call.
   auto *Malloc = dyn_cast<CallInst>(Memset->getArgOperand(0));
-  if (!Malloc || !Malloc->hasOneUse())
+  if (!Malloc)
     return nullptr;
 
   // Is the inner call really malloc()?
@@ -853,6 +849,10 @@
   if (!InnerCallee)
     return nullptr;
 
+  // Check if non-intristic malloc has more than one use
+  if (!InnerCallee->isIntrinsic() && !Malloc->hasOneUse())
+    return nullptr;
+
   LibFunc Func;
   if (!TLI.getLibFunc(*InnerCallee, Func) || !TLI.has(Func) ||
       Func != LibFunc_malloc)
@@ -883,6 +883,10 @@
   if (auto *Calloc = foldMallocMemset(CI, B, *TLI))
     return Calloc;
 
+  if (CI->getCalledFunction()->isIntrinsic()) {
+    return nullptr;
+  }
+
   // memset(p, v, n) -> llvm.memset(align 1 p, v, n)
   Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false);
   B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
@@ -2219,7 +2223,8 @@
       return optimizeLog(CI, Builder);
     case Intrinsic::sqrt:
       return optimizeSqrt(CI, Builder);
-    // TODO: Use foldMallocMemset() with memset intrinsic.
+    case Intrinsic::memset:
+      return optimizeMemSet(CI, Builder);
     default:
       return nullptr;
     }
Index: test/Transforms/InstCombine/memset-1.ll
===================================================================
--- test/Transforms/InstCombine/memset-1.ll
+++ test/Transforms/InstCombine/memset-1.ll
@@ -102,6 +102,16 @@
   ret i8* %memset
 }
 
+define i8* @memset_intristic_malloc(i32 %n) #0 {
+; CHECK-LABEL: @memset_intristic_malloc(
+; CHECK-NEXT:    [[CALLOC:%.*]] = call i8* @calloc(i32 1, i32 [[N:%.*]])
+; CHECK-NEXT:    ret i8* [[CALLOC]]
+;
+  %call = call i8* @malloc(i32 %n)
+  call void @llvm.memset.p0i8.i32(i8* %call, i8 0, i32 %n, i32 1, i1 false)
+  ret i8*%call
+}
+
 attributes #0 = { nounwind ssp uwtable }
 attributes #1 = { nounwind }
 attributes #2 = { nounwind readnone }