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
@@ -1164,8 +1164,10 @@
 
   CallInst *NewCall;
   if (SplatValue) {
+    AAMDNodes AATags;
+    TheStore->getAAMetadata(AATags);
     NewCall = Builder.CreateMemSet(BasePtr, SplatValue, NumBytes,
-                                   MaybeAlign(StoreAlignment));
+                                   MaybeAlign(StoreAlignment), /*isVolatile=*/false, AATags.TBAA, AATags.Scope, AATags.NoAlias);
   } else {
     // Everything is emitted in default address space
     Type *Int8PtrTy = DestInt8PtrTy;
@@ -1382,17 +1384,24 @@
   Value *NumBytes =
       Expander.expandCodeFor(NumBytesS, IntIdxTy, Preheader->getTerminator());
 
+  AAMDNodes AATags;
+  TheLoad->getAAMetadata(AATags);
+  TheStore->getAAMetadata(AATags, /*Merge=*/ true);
+
   CallInst *NewCall = nullptr;
   // Check whether to generate an unordered atomic memcpy:
   //  If the load or store are atomic, then they must necessarily be unordered
   //  by previous checks.
   if (!TheStore->isAtomic() && !TheLoad->isAtomic()) {
     if (UseMemMove)
-      NewCall = Builder.CreateMemMove(StoreBasePtr, StoreAlign, LoadBasePtr,
-                                      LoadAlign, NumBytes);
+      NewCall = Builder.CreateMemMove(
+          StoreBasePtr, StoreAlign, LoadBasePtr, LoadAlign, NumBytes,
+          /*isVolatile=*/ false, AATags.TBAA, AATags.Scope, AATags.NoAlias);
     else
-      NewCall = Builder.CreateMemCpy(StoreBasePtr, StoreAlign, LoadBasePtr,
-                                     LoadAlign, NumBytes);
+      NewCall =
+          Builder.CreateMemCpy(StoreBasePtr, StoreAlign, LoadBasePtr, LoadAlign,
+                               NumBytes, /*isVolatile=*/ false, AATags.TBAA,
+                               AATags.TBAAStruct, AATags.Scope, AATags.NoAlias);
   } else {
     // For now don't support unordered atomic memmove.
     if (UseMemMove)
@@ -1416,7 +1425,8 @@
     // have an alignment but non-atomic loads/stores may not.
     NewCall = Builder.CreateElementUnorderedAtomicMemCpy(
         StoreBasePtr, StoreAlign.getValue(), LoadBasePtr, LoadAlign.getValue(),
-        NumBytes, StoreSize);
+        NumBytes, StoreSize, AATags.TBAA, AATags.TBAAStruct, AATags.Scope,
+        AATags.NoAlias);
   }
   NewCall->setDebugLoc(TheStore->getDebugLoc());
 
diff --git a/llvm/test/Transforms/LoopIdiom/memcpy-tbaa.ll b/llvm/test/Transforms/LoopIdiom/memcpy-tbaa.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/memcpy-tbaa.ll
@@ -0,0 +1,122 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes="loop-idiom" < %s -S | FileCheck %s
+
+define void @looper(double* noalias nocapture readonly %M, double* noalias nocapture %out) {
+; CHECK-LABEL: @looper(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[OUT1:%.*]] = bitcast double* [[OUT:%.*]] to i8*
+; CHECK-NEXT:    [[M2:%.*]] = bitcast double* [[M:%.*]] to i8*
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 [[OUT1]], i8* align 8 [[M2]], i64 256, i1 false), !tbaa [[TBAA0:![0-9]+]]
+; CHECK-NEXT:    br label [[FOR_BODY4:%.*]]
+; CHECK:       for.body4:
+; CHECK-NEXT:    [[J_020:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[FOR_BODY4]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, double* [[M]], i64 [[J_020]]
+; CHECK-NEXT:    [[A0:%.*]] = load double, double* [[ARRAYIDX]], align 8, !tbaa [[TBAA0]]
+; CHECK-NEXT:    [[ARRAYIDX8:%.*]] = getelementptr inbounds double, double* [[OUT]], i64 [[J_020]]
+; CHECK-NEXT:    [[INC]] = add nuw nsw i64 [[J_020]], 1
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i64 [[J_020]], 31
+; CHECK-NEXT:    br i1 [[CMP2]], label [[FOR_BODY4]], label [[FOR_COND_CLEANUP:%.*]]
+; CHECK:       for.cond.cleanup:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body4
+
+for.body4:                                        ; preds = %for.cond1.preheader, %for.body4
+  %j.020 = phi i64 [ 0, %entry ], [ %inc, %for.body4 ]
+  %arrayidx = getelementptr inbounds double, double* %M, i64 %j.020
+  %a0 = load double, double* %arrayidx, align 8, !tbaa !5
+  %arrayidx8 = getelementptr inbounds double, double* %out, i64 %j.020
+  store double %a0, double* %arrayidx8, align 8, !tbaa !5
+  %inc = add nuw nsw i64 %j.020, 1
+  %cmp2 = icmp ult i64 %j.020, 31
+  br i1 %cmp2, label %for.body4, label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond.cleanup3
+  ret void
+}
+
+
+define void @looperBadMerge(double* noalias nocapture readonly %M, double* noalias nocapture %out) {
+; CHECK-LABEL: @looperBadMerge(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[OUT1:%.*]] = bitcast double* [[OUT:%.*]] to i8*
+; CHECK-NEXT:    [[M2:%.*]] = bitcast double* [[M:%.*]] to i8*
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 [[OUT1]], i8* align 8 [[M2]], i64 256, i1 false), !tbaa [[TBAAF:![0-9]+]]
+; CHECK-NEXT:    br label [[FOR_BODY4:%.*]]
+; CHECK:       for.body4:
+; CHECK-NEXT:    [[J_020:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[FOR_BODY4]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, double* [[M]], i64 [[J_020]]
+; CHECK-NEXT:    [[A0:%.*]] = load double, double* [[ARRAYIDX]], align 8, !tbaa [[TBAA0]]
+; CHECK-NEXT:    [[ARRAYIDX8:%.*]] = getelementptr inbounds double, double* [[OUT]], i64 [[J_020]]
+; CHECK-NEXT:    [[INC]] = add nuw nsw i64 [[J_020]], 1
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i64 [[J_020]], 31
+; CHECK-NEXT:    br i1 [[CMP2]], label [[FOR_BODY4]], label [[FOR_COND_CLEANUP:%.*]]
+; CHECK:       for.cond.cleanup:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body4
+
+for.body4:                                        ; preds = %for.cond1.preheader, %for.body4
+  %j.020 = phi i64 [ 0, %entry ], [ %inc, %for.body4 ]
+  %arrayidx = getelementptr inbounds double, double* %M, i64 %j.020
+  %a0 = load double, double* %arrayidx, align 8, !tbaa !5
+  %arrayidx8 = getelementptr inbounds double, double* %out, i64 %j.020
+  store double %a0, double* %arrayidx8, align 8, !tbaa !3
+  %inc = add nuw nsw i64 %j.020, 1
+  %cmp2 = icmp ult i64 %j.020, 31
+  br i1 %cmp2, label %for.body4, label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond.cleanup3
+  ret void
+}
+
+define void @looperGoodMerge(double* noalias nocapture readonly %M, double* noalias nocapture %out) {
+; CHECK-LABEL: @looperGoodMerge(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[OUT1:%.*]] = bitcast double* [[OUT:%.*]] to i8*
+; CHECK-NEXT:    [[M2:%.*]] = bitcast double* [[M:%.*]] to i8*
+; CHECK-NOT:     !tbaa
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 [[OUT1]], i8* align 8 [[M2]], i64 256, i1 false) 
+; CHECK-NEXT:    br label [[FOR_BODY4:%.*]]
+; CHECK:       for.body4:
+; CHECK-NEXT:    [[J_020:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[FOR_BODY4]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, double* [[M]], i64 [[J_020]]
+; CHECK-NEXT:    [[A0:%.*]] = load double, double* [[ARRAYIDX]], align 8, !tbaa [[TBAA0]]
+; CHECK-NEXT:    [[ARRAYIDX8:%.*]] = getelementptr inbounds double, double* [[OUT]], i64 [[J_020]]
+; CHECK-NEXT:    [[INC]] = add nuw nsw i64 [[J_020]], 1
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i64 [[J_020]], 31
+; CHECK-NEXT:    br i1 [[CMP2]], label [[FOR_BODY4]], label [[FOR_COND_CLEANUP:%.*]]
+; CHECK:       for.cond.cleanup:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body4
+
+for.body4:                                        ; preds = %for.cond1.preheader, %for.body4
+  %j.020 = phi i64 [ 0, %entry ], [ %inc, %for.body4 ]
+  %arrayidx = getelementptr inbounds double, double* %M, i64 %j.020
+  %a0 = load double, double* %arrayidx, align 8, !tbaa !5
+  %arrayidx8 = getelementptr inbounds double, double* %out, i64 %j.020
+  store double %a0, double* %arrayidx8, align 8
+  %inc = add nuw nsw i64 %j.020, 1
+  %cmp2 = icmp ult i64 %j.020, 31
+  br i1 %cmp2, label %for.body4, label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond.cleanup3
+  ret void
+}
+
+; CHECK: [[TBAA0]] = !{[[TBAA1:.+]], [[TBAA1]], i64 0}
+; CHECK: [[TBAA1]] = !{!"double", [[TBAA2:.+]], i64 0}
+; CHECK: [[TBAA2]] = !{!"omnipotent char", [[TBAA3:.+]], i64 0}
+
+; CHECK: [[TBAAF]] = !{[[TBAA2:.+]], [[TBAA2]], i64 0}
+
+!3 = !{!4, !4, i64 0}
+!4 = !{!"float", !7, i64 0}
+!5 = !{!6, !6, i64 0}
+!6 = !{!"double", !7, i64 0}
+!7 = !{!"omnipotent char", !8, i64 0}
+!8 = !{!"Simple C++ TBAA"}
diff --git a/llvm/test/Transforms/LoopIdiom/memset-tbaa.ll b/llvm/test/Transforms/LoopIdiom/memset-tbaa.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/memset-tbaa.ll
@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes="loop-idiom" < %s -S | FileCheck %s
+
+
+define dso_local void @double_memset(i8* nocapture %p) {
+; CHECK-LABEL: @double_memset(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    call void @llvm.memset.p0i8.i64(i8* align 1 [[P:%.*]], i8 0, i64 16, i1 false), !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:    [[INCDEC_PTR1:.+]] = getelementptr inbounds i8, i8* [[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_LOOPEXIT:%.*]], 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 i8, i8* %p, i64 %i.07
+  store i8 0, i8* %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
+}
+
+; CHECK: [[TBAA0]] = !{[[TBAA1:.+]], [[TBAA1]], i64 0}
+; CHECK: [[TBAA1]] = !{!"double", [[TBAA2:.+]], i64 0}
+; CHECK: [[TBAA2]] = !{!"omnipotent char", [[TBAA3:.+]], i64 0}
+
+!5 = !{!6, !6, i64 0}
+!6 = !{!"double", !7, i64 0}
+!7 = !{!"omnipotent char", !8, i64 0}
+!8 = !{!"Simple C++ TBAA"}