diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -1088,6 +1088,13 @@
         BasePtr, SplatValue, NumBytes, MaybeAlign(StoreAlignment),
         /*isVolatile=*/false, AATags.TBAA, AATags.Scope, AATags.NoAlias);
   } else if (isLibFuncEmittable(M, TLI, LibFunc_memset_pattern16)) {
+    AAMDNodes AATags = TheStore->getAAMetadata();
+    for (Instruction *Store : Stores)
+      AATags = AATags.merge(Store->getAAMetadata());
+    if (auto CI = dyn_cast<ConstantInt>(NumBytes))
+      AATags = AATags.extendTo(CI->getZExtValue());
+    else
+      AATags = AATags.extendTo(-1);
     // Everything is emitted in default address space
     Type *Int8PtrTy = DestInt8PtrTy;
 
@@ -1105,6 +1112,16 @@
     GV->setAlignment(Align(16));
     Value *PatternPtr = ConstantExpr::getBitCast(GV, Int8PtrTy);
     NewCall = Builder.CreateCall(MSP, {BasePtr, PatternPtr, NumBytes});
+    
+    // Set the TBAA info if present.
+    if (AATags.TBAA)
+      NewCall->setMetadata(LLVMContext::MD_tbaa, AATags.TBAA);
+
+    if (AATags.Scope)
+      NewCall->setMetadata(LLVMContext::MD_alias_scope, AATags.Scope);
+
+    if (AATags.NoAlias)
+      NewCall->setMetadata(LLVMContext::MD_noalias, AATags.NoAlias);
   } else
     return Changed;
 
diff --git a/llvm/test/Transforms/LoopIdiom/memset-pattern-tbaa.ll b/llvm/test/Transforms/LoopIdiom/memset-pattern-tbaa.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/memset-pattern-tbaa.ll
@@ -0,0 +1,112 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes="loop-idiom" < %s -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+
+target triple = "x86_64-apple-darwin10.0.0"
+
+
+define dso_local void @double_memset(ptr nocapture %p) {
+; CHECK-LABEL: @double_memset(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    call void @memset_pattern16(ptr [[P:%.*]], ptr @.memset_pattern, i64 128), !tbaa [[TBAA0:![0-9]+]]
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.cond.cleanup:
+; CHECK-NEXT:    ret void
+; CHECK:       for.body:
+; CHECK-NEXT:    [[I_07:%.*]] = phi i64 [ [[INC:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[PTR1:%.*]] = getelementptr inbounds double, ptr [[P]], i64 [[I_07]]
+; CHECK-NEXT:    [[INC]] = add nuw nsw i64 [[I_07]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INC]], 16
+; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
+;
+entry:
+  br label %for.body
+
+for.cond.cleanup:
+  ret void
+
+for.body:
+  %i.07 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
+  %ptr1 = getelementptr inbounds double, ptr %p, i64 %i.07
+  store double 3.14159e+00, ptr %ptr1, align 1, !tbaa !5
+  %inc = add nuw nsw i64 %i.07, 1
+  %exitcond.not = icmp eq i64 %inc, 16
+  br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+
+define dso_local void @struct_memset(ptr nocapture %p) {
+; CHECK-LABEL: @struct_memset(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    call void @memset_pattern16(ptr [[P:%.*]], ptr @.memset_pattern.1, i64 128), !tbaa [[TBAA4:![0-9]+]]
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.cond.cleanup:
+; CHECK-NEXT:    ret void
+; CHECK:       for.body:
+; CHECK-NEXT:    [[I_07:%.*]] = phi i64 [ [[INC:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[PTR1:%.*]] = getelementptr inbounds double, ptr [[P]], i64 [[I_07]]
+; CHECK-NEXT:    [[INC]] = add nuw nsw i64 [[I_07]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INC]], 16
+; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
+;
+entry:
+  br label %for.body
+
+for.cond.cleanup:
+  ret void
+
+for.body:
+  %i.07 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
+  %ptr1 = getelementptr inbounds double, ptr %p, i64 %i.07
+  store double 3.14159e+00, ptr %ptr1, align 1, !tbaa !10
+  %inc = add nuw nsw i64 %i.07, 1
+  %exitcond.not = icmp eq i64 %inc, 16
+  br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+define dso_local void @var_memset(ptr nocapture %p, i64 %len) {
+; CHECK-LABEL: @var_memset(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = shl nuw i64 [[LEN:%.*]], 3
+; CHECK-NEXT:    call void @memset_pattern16(ptr [[P:%.*]], ptr @.memset_pattern.2, i64 [[TMP0]])
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.cond.cleanup:
+; CHECK-NEXT:    ret void
+; CHECK:       for.body:
+; CHECK-NEXT:    [[I_07:%.*]] = phi i64 [ [[INC:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[PTR1:%.*]] = getelementptr inbounds double, ptr [[P]], i64 [[I_07]]
+; CHECK-NEXT:    [[INC]] = add nuw nsw i64 [[I_07]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INC]], [[LEN]]
+; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
+;
+entry:
+  br label %for.body
+
+for.cond.cleanup:
+  ret void
+
+for.body:
+  %i.07 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
+  %ptr1 = getelementptr inbounds double, ptr %p, i64 %i.07
+  store double 3.14159e+00, ptr %ptr1, align 1, !tbaa !10
+  %inc = add nuw nsw i64 %i.07, 1
+  %exitcond.not = icmp eq i64 %inc, %len
+  br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+!5 = !{!6, !6, i64 0}
+!6 = !{!"double", !7, i64 0}
+!7 = !{!"omnipotent char", !8, i64 0}
+!8 = !{!"Simple C++ TBAA"}
+
+!15 = !{!8, i64 0, !"omnipotent char"}
+!17 = !{!15, i64 8, !"double"}
+!9 = !{!15, i64 32, !"_ZTS1A", !17, i64 0, i64 8, !17, i64 8, i64 8, !17, i64 16, i64 8, !17, i64 24, i64 8}
+!10 = !{!9, !17, i64 0, i64 1}
+
+!18 = !{!19, !20, i64 0}
+!19 = !{!"A", !20, i64 0, !22, i64 8}
+!20 = !{!"any pointer", !7, i64 0}
+!21 = !{!22, !20, i64 0}
+!22 = !{!"B", !20, i64 0}