Index: lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
===================================================================
--- lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -2764,18 +2764,24 @@
     return;
   }
   case ISD::Constant: {
-    // Materialize zero constants as copies from WZR/XZR.  This allows
-    // the coalescer to propagate these into other instructions.
+    // If all uses of zero constants are copies to virutal regs, replace the
+    // constants with WZR/XZR.  Otherwise, materialize zero constants as copies
+    // from WZR/XZR and allow the coalescer to propagate these into other
+    // instructions.
     ConstantSDNode *ConstNode = cast<ConstantSDNode>(Node);
     if (ConstNode->isNullValue()) {
-      if (VT == MVT::i32) {
-        SDValue New = CurDAG->getCopyFromReg(
-            CurDAG->getEntryNode(), SDLoc(Node), AArch64::WZR, MVT::i32);
-        ReplaceNode(Node, New.getNode());
-        return;
-      } else if (VT == MVT::i64) {
-        SDValue New = CurDAG->getCopyFromReg(
-            CurDAG->getEntryNode(), SDLoc(Node), AArch64::XZR, MVT::i64);
+      if (VT == MVT::i32 || VT == MVT::i64) {
+        unsigned ZReg = (VT == MVT::i32) ? AArch64::WZR : AArch64::XZR;
+        SDValue New;
+        if (llvm::all_of(Node->uses(), [&](SDNode *User) {
+              return (User->getOpcode() == ISD::CopyToReg &&
+                      TargetRegisterInfo::isVirtualRegister(
+                          cast<RegisterSDNode>(User->getOperand(1))->getReg()));
+            }))
+          New = CurDAG->getRegister(ZReg, VT);
+        else
+          New = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), SDLoc(Node),
+                                       ZReg, VT);
         ReplaceNode(Node, New.getNode());
         return;
       }
Index: test/CodeGen/AArch64/arm64-addr-type-promotion.ll
===================================================================
--- test/CodeGen/AArch64/arm64-addr-type-promotion.ll
+++ test/CodeGen/AArch64/arm64-addr-type-promotion.ll
@@ -28,6 +28,7 @@
 ; Next BB
 ; CHECK: ldrb [[LOADEDVAL3:w[0-9]+]], {{\[}}[[BLOCKBASE1]], #2]
 ; CHECK-NEXT: ldrb [[LOADEDVAL4:w[0-9]+]], {{\[}}[[BLOCKBASE2]], #2]
+; CHECK-NEXT: mov w0, wzr
 ; CHECK-NEXT: cmp [[LOADEDVAL3]], [[LOADEDVAL4]]
 entry:
   %idxprom = sext i32 %i1 to i64
Index: test/CodeGen/AArch64/arm64-cse.ll
===================================================================
--- test/CodeGen/AArch64/arm64-cse.ll
+++ test/CodeGen/AArch64/arm64-cse.ll
@@ -10,7 +10,7 @@
 ; CHECK: subs
 ; CHECK-NOT: cmp
 ; CHECK-NOT: sub
-; CHECK: b.ge
+; CHECK: b.lt
 ; CHECK: sub
 ; CHECK: sub
 ; CHECK-NOT: sub
Index: test/CodeGen/AArch64/copy-zero-reg.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/copy-zero-reg.ll
@@ -0,0 +1,45 @@
+; RUN: llc < %s -verify-machineinstrs -mtriple=aarch64-none-linux-gnu | FileCheck %s
+
+; Verify no tiny block has only one mov wzr instruction
+define void @unroll_by_2(i32 %trip_count, i32* %p) {
+; CHECK-LABEL: unroll_by_2
+; CHECK: // %for.body.lr.ph
+; CHECK: 	mov	 w{{[0-9]+}}, wzr
+; CHECK: // %for.body.lr.ph.new
+; CHECK: // %for.body
+; CHECK: // %sw.epilog.loopexit
+; CHECK: // %for.body.epil
+; CHECK: // %exit
+; CHECK-NEXT:   ret
+for.body.lr.ph:
+  %xtraiter = and i32 %trip_count, 1
+  %cmp = icmp eq i32 %trip_count, 1
+  br i1 %cmp, label %sw.epilog.loopexit, label %for.body.lr.ph.new
+
+for.body.lr.ph.new:
+  %unroll_iter = sub nsw i32 %trip_count, %xtraiter
+  br label %for.body
+
+for.body:
+  %indvars = phi i32 [ 0, %for.body.lr.ph.new ], [ %indvars.next, %for.body ]
+  %niter = phi i32 [ %unroll_iter, %for.body.lr.ph.new ], [ %niter.nsub, %for.body ]
+  %array = getelementptr inbounds i32, i32 * %p, i32 %indvars
+  store  i32 %niter, i32* %array
+  %indvars.next = add i32 %indvars, 2
+  %niter.nsub = add i32 %niter, -2
+  %niter.ncmp = icmp eq i32 %niter.nsub, 0
+  br i1 %niter.ncmp, label %sw.epilog.loopexit, label %for.body
+
+sw.epilog.loopexit:
+  %indvars.unr = phi i32 [ 0, %for.body.lr.ph ], [ %indvars.next, %for.body ]
+  %lcmp.mod = icmp eq i32 %xtraiter, 0
+  br i1 %lcmp.mod, label %exit, label %for.body.epil
+
+for.body.epil:
+  %array.epil = getelementptr inbounds i32, i32* %p, i32 %indvars.unr
+  store  i32 %indvars.unr, i32* %array.epil
+  br label %exit
+
+exit:
+  ret void
+}
Index: test/CodeGen/AArch64/i128-fast-isel-fallback.ll
===================================================================
--- test/CodeGen/AArch64/i128-fast-isel-fallback.ll
+++ test/CodeGen/AArch64/i128-fast-isel-fallback.ll
@@ -10,7 +10,7 @@
 ; registers that make up the i128 pair
 
 ; CHECK:  mov  x0, xzr
-; CHECK:  mov  x1, x0
+; CHECK:  mov  x1, xzr
 ; CHECK:  bl  _test2
 
 }