Index: lib/CodeGen/MachineCopyPropagation.cpp
===================================================================
--- lib/CodeGen/MachineCopyPropagation.cpp
+++ lib/CodeGen/MachineCopyPropagation.cpp
@@ -285,18 +285,28 @@
     // defined registers.
     if (RegMask) {
       // Erase any MaybeDeadCopies whose destination register is clobbered.
-      for (MachineInstr *MaybeDead : MaybeDeadCopies) {
+      for (SmallSetVector<MachineInstr *, 8>::iterator DI =
+               MaybeDeadCopies.begin();
+           DI != MaybeDeadCopies.end();) {
+        MachineInstr *MaybeDead = *DI;
         unsigned Reg = MaybeDead->getOperand(0).getReg();
         assert(!MRI->isReserved(Reg));
-        if (!RegMask->clobbersPhysReg(Reg))
+
+        if (!RegMask->clobbersPhysReg(Reg)) {
+          ++DI;
           continue;
+        }
+
         DEBUG(dbgs() << "MCP: Removing copy due to regmask clobbering: ";
               MaybeDead->dump());
+
+        // erase() will returns the next valid iterator pointing to the next
+        // element after the erased one.
+        DI = MaybeDeadCopies.erase(DI);
         MaybeDead->eraseFromParent();
         Changed = true;
         ++NumDeletes;
       }
-      MaybeDeadCopies.clear();
 
       removeClobberedRegsFromMap(AvailCopyMap, *RegMask);
       removeClobberedRegsFromMap(CopyMap, *RegMask);
@@ -348,3 +358,4 @@
 
   return Changed;
 }
+
Index: test/CodeGen/MIR/AArch64/machine-dead-copy.mir
===================================================================
--- /dev/null
+++ test/CodeGen/MIR/AArch64/machine-dead-copy.mir
@@ -0,0 +1,67 @@
+
+# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass machine-cp  -verify-machineinstrs  -o /dev/null %s 2>&1 | FileCheck %s
+
+--- |
+  define i32 @copyprop1(i32 %a, i32 %b) { ret i32 %a }
+  define i32 @copyprop2(i32 %a, i32 %b) { ret i32 %a }
+  define i32 @copyprop3(i32 %a, i32 %b) { ret i32 %a }
+  define i32 @copyprop4(i32 %a, i32 %b) { ret i32 %a }
+  declare i32 @foo(i32)
+...
+---
+# The first copy is dead copy which is not used.
+# CHECK-LABEL: name: copyprop1
+# CHECK: bb.0:
+# CHECK-NOT: %w20 = COPY
+name:            copyprop1
+body:             |
+  bb.0:
+    liveins: %w0,  %w1
+    %w20 = COPY %w1
+    BL @foo, csr_aarch64_aapcs, implicit %w0, implicit-def %w0
+    RET_ReallyLR implicit %w0
+...
+---
+# The first copy is not a dead copy which is used in the second copy after the
+# call.
+# CHECK-LABEL: name: copyprop2
+# CHECK: bb.0:
+# CHECK: %w20 = COPY
+name:            copyprop2
+body:             |
+  bb.0:
+    liveins: %w0,  %w1
+    %w20 = COPY %w1
+    BL @foo, csr_aarch64_aapcs, implicit %w0, implicit-def %w0
+    %w0 = COPY %w20
+    RET_ReallyLR implicit %w0
+...
+---
+# Both the first and second copy are dead copies which are not used.
+# CHECK-LABEL: name: copyprop3
+# CHECK: bb.0:
+# CHECK-NOT: COPY
+name:            copyprop3
+body:             |
+  bb.0:
+    liveins: %w0,  %w1
+    %w20 = COPY %w1
+    BL @foo, csr_aarch64_aapcs, implicit %w0, implicit-def %w0
+    %w20 = COPY %w0
+    RET_ReallyLR implicit %w0
+...
+# The second copy is removed as a NOP copy, after then the first copy become
+# dead which should be removed as well.
+# CHECK-LABEL: name: copyprop4
+# CHECK: bb.0:
+# CHECK-NOT: COPY
+name:            copyprop4
+body:             |
+  bb.0:
+    liveins: %w0,  %w1
+    %w20 = COPY %w0
+    %w0 = COPY %w20
+    BL @foo, csr_aarch64_aapcs, implicit %w0, implicit-def %w0
+    RET_ReallyLR implicit %w0
+...
+