diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -268,6 +268,11 @@
     MaxAddressUsersToScan("cgp-max-address-users-to-scan", cl::init(100),
                           cl::Hidden,
                           cl::desc("Max number of address users to look at"));
+
+static cl::opt<bool>
+    DisableDeletePHIs("disable-cgp-delete-phis", cl::Hidden, cl::init(false),
+                      cl::desc("Disable elimination of dead PHI nodes."));
+
 namespace {
 
 enum ExtType {
@@ -878,8 +883,12 @@
   // as we remove them.
   // Note that this intentionally skips the entry block.
   SmallVector<WeakTrackingVH, 16> Blocks;
-  for (auto &Block : llvm::drop_begin(F))
+  for (auto &Block : llvm::drop_begin(F)) {
+    // Delete phi nodes that could block deleting other empty blocks.
+    if (!DisableDeletePHIs)
+      MadeChange |= DeleteDeadPHIs(&Block, TLInfo);
     Blocks.push_back(&Block);
+  }
 
   for (auto &Block : Blocks) {
     BasicBlock *BB = cast_or_null<BasicBlock>(Block);
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-lse2.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-lse2.ll
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-lse2.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-lse2.ll
@@ -28,7 +28,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -59,7 +59,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -90,7 +90,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -121,7 +121,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -152,7 +152,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -183,7 +183,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -214,7 +214,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -245,7 +245,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -276,7 +276,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -307,7 +307,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -338,7 +338,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -369,7 +369,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -400,7 +400,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -431,7 +431,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -462,7 +462,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -493,7 +493,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -524,7 +524,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -555,7 +555,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -586,7 +586,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -617,7 +617,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -648,7 +648,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -679,7 +679,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -710,7 +710,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -741,7 +741,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -772,7 +772,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -803,7 +803,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -834,7 +834,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -865,7 +865,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -896,7 +896,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -927,7 +927,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -957,7 +957,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -987,7 +987,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1017,7 +1017,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1047,7 +1047,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1077,7 +1077,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1107,7 +1107,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1137,7 +1137,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1167,7 +1167,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1197,7 +1197,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1227,7 +1227,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1257,7 +1257,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1287,7 +1287,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1317,7 +1317,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1347,7 +1347,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1377,7 +1377,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1407,7 +1407,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1437,7 +1437,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1467,7 +1467,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1497,7 +1497,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1527,7 +1527,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1557,7 +1557,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1587,7 +1587,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1617,7 +1617,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1647,7 +1647,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1677,7 +1677,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1707,7 +1707,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1737,7 +1737,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1767,7 +1767,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1797,7 +1797,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1827,7 +1827,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -2428,7 +2428,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2459,7 +2459,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2490,7 +2490,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2521,7 +2521,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2552,7 +2552,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2583,7 +2583,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2614,7 +2614,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2645,7 +2645,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2676,7 +2676,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2707,7 +2707,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2738,7 +2738,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2769,7 +2769,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2800,7 +2800,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2831,7 +2831,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2862,7 +2862,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-rcpc.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-rcpc.ll
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-rcpc.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-rcpc.ll
@@ -28,7 +28,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -59,7 +59,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -90,7 +90,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -121,7 +121,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -152,7 +152,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -183,7 +183,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -214,7 +214,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -245,7 +245,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -276,7 +276,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -307,7 +307,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -338,7 +338,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -369,7 +369,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -400,7 +400,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -431,7 +431,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -462,7 +462,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -493,7 +493,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -524,7 +524,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -555,7 +555,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -586,7 +586,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -617,7 +617,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -648,7 +648,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -679,7 +679,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -710,7 +710,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -741,7 +741,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -772,7 +772,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -803,7 +803,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -834,7 +834,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -865,7 +865,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -896,7 +896,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -927,7 +927,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -957,7 +957,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -987,7 +987,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1017,7 +1017,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1047,7 +1047,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1077,7 +1077,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1107,7 +1107,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1137,7 +1137,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1167,7 +1167,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1197,7 +1197,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1227,7 +1227,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1257,7 +1257,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1287,7 +1287,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1317,7 +1317,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1347,7 +1347,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1377,7 +1377,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1407,7 +1407,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1437,7 +1437,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1467,7 +1467,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1497,7 +1497,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1527,7 +1527,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1557,7 +1557,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1587,7 +1587,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1617,7 +1617,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1647,7 +1647,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1677,7 +1677,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1707,7 +1707,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1737,7 +1737,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1767,7 +1767,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1797,7 +1797,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1827,7 +1827,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -2428,7 +2428,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2459,7 +2459,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2490,7 +2490,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2521,7 +2521,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2552,7 +2552,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2583,7 +2583,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2614,7 +2614,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2645,7 +2645,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2676,7 +2676,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2707,7 +2707,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2738,7 +2738,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2769,7 +2769,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2800,7 +2800,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2831,7 +2831,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2862,7 +2862,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-rcpc3.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-rcpc3.ll
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-rcpc3.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-rcpc3.ll
@@ -28,7 +28,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -59,7 +59,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -90,7 +90,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -121,7 +121,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -152,7 +152,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -183,7 +183,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -214,7 +214,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -245,7 +245,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -276,7 +276,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -307,7 +307,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -338,7 +338,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -369,7 +369,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -400,7 +400,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -431,7 +431,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -462,7 +462,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -493,7 +493,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -524,7 +524,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -555,7 +555,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -586,7 +586,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -617,7 +617,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -648,7 +648,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -679,7 +679,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -710,7 +710,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -741,7 +741,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -772,7 +772,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -803,7 +803,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -834,7 +834,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -865,7 +865,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -896,7 +896,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -927,7 +927,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -957,7 +957,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -987,7 +987,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1017,7 +1017,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1047,7 +1047,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1077,7 +1077,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1107,7 +1107,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1137,7 +1137,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1167,7 +1167,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1197,7 +1197,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1227,7 +1227,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1257,7 +1257,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1287,7 +1287,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1317,7 +1317,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1347,7 +1347,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1377,7 +1377,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1407,7 +1407,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1437,7 +1437,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1467,7 +1467,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1497,7 +1497,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1527,7 +1527,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1557,7 +1557,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1587,7 +1587,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1617,7 +1617,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1647,7 +1647,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1677,7 +1677,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1707,7 +1707,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1737,7 +1737,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1767,7 +1767,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1797,7 +1797,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1827,7 +1827,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -2428,7 +2428,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2459,7 +2459,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2490,7 +2490,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2521,7 +2521,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2552,7 +2552,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2583,7 +2583,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2614,7 +2614,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2645,7 +2645,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2676,7 +2676,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2707,7 +2707,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2738,7 +2738,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2769,7 +2769,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2800,7 +2800,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2831,7 +2831,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2862,7 +2862,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-v8a.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-v8a.ll
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-v8a.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64-cmpxchg-v8a.ll
@@ -28,7 +28,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -59,7 +59,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -90,7 +90,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -121,7 +121,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -152,7 +152,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -183,7 +183,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -214,7 +214,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -245,7 +245,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -276,7 +276,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -307,7 +307,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -338,7 +338,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -369,7 +369,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -400,7 +400,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -431,7 +431,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -462,7 +462,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -493,7 +493,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -524,7 +524,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -555,7 +555,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -586,7 +586,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -617,7 +617,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -648,7 +648,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -679,7 +679,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -710,7 +710,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -741,7 +741,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -772,7 +772,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -803,7 +803,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -834,7 +834,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -865,7 +865,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -896,7 +896,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -927,7 +927,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -957,7 +957,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -987,7 +987,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1017,7 +1017,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1047,7 +1047,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1077,7 +1077,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1107,7 +1107,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1137,7 +1137,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1167,7 +1167,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1197,7 +1197,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1227,7 +1227,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1257,7 +1257,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1287,7 +1287,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1317,7 +1317,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1347,7 +1347,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1377,7 +1377,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1407,7 +1407,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1437,7 +1437,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1467,7 +1467,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1497,7 +1497,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1527,7 +1527,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1557,7 +1557,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1587,7 +1587,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1617,7 +1617,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1647,7 +1647,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1677,7 +1677,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1707,7 +1707,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1737,7 +1737,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1767,7 +1767,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1797,7 +1797,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1827,7 +1827,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -2428,7 +2428,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2459,7 +2459,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2490,7 +2490,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2521,7 +2521,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2552,7 +2552,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2583,7 +2583,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2614,7 +2614,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2645,7 +2645,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2676,7 +2676,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2707,7 +2707,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2738,7 +2738,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2769,7 +2769,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2800,7 +2800,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2831,7 +2831,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2862,7 +2862,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-lse2.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-lse2.ll
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-lse2.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-lse2.ll
@@ -28,7 +28,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -59,7 +59,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -90,7 +90,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -121,7 +121,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -152,7 +152,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -183,7 +183,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -214,7 +214,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -245,7 +245,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -276,7 +276,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -307,7 +307,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -338,7 +338,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -369,7 +369,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -400,7 +400,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -431,7 +431,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -462,7 +462,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -493,7 +493,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -524,7 +524,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -555,7 +555,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -586,7 +586,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -617,7 +617,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -648,7 +648,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -679,7 +679,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -710,7 +710,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -741,7 +741,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -772,7 +772,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -803,7 +803,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -834,7 +834,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -865,7 +865,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -896,7 +896,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -927,7 +927,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -957,7 +957,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -987,7 +987,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1017,7 +1017,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1047,7 +1047,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1077,7 +1077,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1107,7 +1107,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1137,7 +1137,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1167,7 +1167,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1197,7 +1197,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1227,7 +1227,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1257,7 +1257,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1287,7 +1287,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1317,7 +1317,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1347,7 +1347,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1377,7 +1377,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1407,7 +1407,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1437,7 +1437,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1467,7 +1467,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1497,7 +1497,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1527,7 +1527,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1557,7 +1557,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1587,7 +1587,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1617,7 +1617,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1647,7 +1647,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1677,7 +1677,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1707,7 +1707,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1737,7 +1737,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1767,7 +1767,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1797,7 +1797,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1827,7 +1827,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -2428,7 +2428,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2459,7 +2459,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2490,7 +2490,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2521,7 +2521,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2552,7 +2552,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2583,7 +2583,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2614,7 +2614,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2645,7 +2645,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2676,7 +2676,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2707,7 +2707,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2738,7 +2738,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2769,7 +2769,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2800,7 +2800,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2831,7 +2831,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2862,7 +2862,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-rcpc.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-rcpc.ll
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-rcpc.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-rcpc.ll
@@ -28,7 +28,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -59,7 +59,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -90,7 +90,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -121,7 +121,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -152,7 +152,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -183,7 +183,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -214,7 +214,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -245,7 +245,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -276,7 +276,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -307,7 +307,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -338,7 +338,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -369,7 +369,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -400,7 +400,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -431,7 +431,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -462,7 +462,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -493,7 +493,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -524,7 +524,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -555,7 +555,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -586,7 +586,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -617,7 +617,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -648,7 +648,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -679,7 +679,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -710,7 +710,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -741,7 +741,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -772,7 +772,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -803,7 +803,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -834,7 +834,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -865,7 +865,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -896,7 +896,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -927,7 +927,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -957,7 +957,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -987,7 +987,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1017,7 +1017,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1047,7 +1047,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1077,7 +1077,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1107,7 +1107,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1137,7 +1137,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1167,7 +1167,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1197,7 +1197,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1227,7 +1227,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1257,7 +1257,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1287,7 +1287,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1317,7 +1317,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1347,7 +1347,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1377,7 +1377,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1407,7 +1407,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1437,7 +1437,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1467,7 +1467,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1497,7 +1497,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1527,7 +1527,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1557,7 +1557,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1587,7 +1587,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1617,7 +1617,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1647,7 +1647,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1677,7 +1677,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1707,7 +1707,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1737,7 +1737,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1767,7 +1767,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1797,7 +1797,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1827,7 +1827,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -2428,7 +2428,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2459,7 +2459,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2490,7 +2490,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2521,7 +2521,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2552,7 +2552,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2583,7 +2583,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2614,7 +2614,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2645,7 +2645,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2676,7 +2676,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2707,7 +2707,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2738,7 +2738,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2769,7 +2769,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2800,7 +2800,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2831,7 +2831,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2862,7 +2862,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-rcpc3.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-rcpc3.ll
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-rcpc3.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-rcpc3.ll
@@ -28,7 +28,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -59,7 +59,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -90,7 +90,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -121,7 +121,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -152,7 +152,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -183,7 +183,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -214,7 +214,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -245,7 +245,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -276,7 +276,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -307,7 +307,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -338,7 +338,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -369,7 +369,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -400,7 +400,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -431,7 +431,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -462,7 +462,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -493,7 +493,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -524,7 +524,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -555,7 +555,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -586,7 +586,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -617,7 +617,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -648,7 +648,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -679,7 +679,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -710,7 +710,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -741,7 +741,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -772,7 +772,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -803,7 +803,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -834,7 +834,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -865,7 +865,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -896,7 +896,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -927,7 +927,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -957,7 +957,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -987,7 +987,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1017,7 +1017,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1047,7 +1047,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1077,7 +1077,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1107,7 +1107,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1137,7 +1137,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1167,7 +1167,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1197,7 +1197,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1227,7 +1227,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1257,7 +1257,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1287,7 +1287,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1317,7 +1317,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1347,7 +1347,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1377,7 +1377,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1407,7 +1407,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1437,7 +1437,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1467,7 +1467,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1497,7 +1497,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1527,7 +1527,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1557,7 +1557,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1587,7 +1587,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1617,7 +1617,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1647,7 +1647,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1677,7 +1677,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1707,7 +1707,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1737,7 +1737,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1767,7 +1767,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1797,7 +1797,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1827,7 +1827,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -2428,7 +2428,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2459,7 +2459,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2490,7 +2490,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2521,7 +2521,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2552,7 +2552,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2583,7 +2583,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2614,7 +2614,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2645,7 +2645,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2676,7 +2676,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2707,7 +2707,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2738,7 +2738,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2769,7 +2769,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2800,7 +2800,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2831,7 +2831,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2862,7 +2862,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-v8a.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-v8a.ll
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-v8a.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-cmpxchg-v8a.ll
@@ -28,7 +28,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -59,7 +59,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -90,7 +90,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -121,7 +121,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -152,7 +152,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -183,7 +183,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -214,7 +214,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -245,7 +245,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -276,7 +276,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -307,7 +307,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -338,7 +338,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -369,7 +369,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -400,7 +400,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -431,7 +431,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -462,7 +462,7 @@
 ; -O1-LABEL: cmpxchg_i8_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -493,7 +493,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -524,7 +524,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -555,7 +555,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new monotonic seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -586,7 +586,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -617,7 +617,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stxrh w9, w1, [x2]
+; -O1:    stxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -648,7 +648,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acquire seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -679,7 +679,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_monotonic_weak:
 ; -O1:    ldxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -710,7 +710,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -741,7 +741,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_release_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new release seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -772,7 +772,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -803,7 +803,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -834,7 +834,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new acq_rel seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -865,7 +865,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst monotonic, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -896,7 +896,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst acquire, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -927,7 +927,7 @@
 ; -O1-LABEL: cmpxchg_i16_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrh w8, [x2]
 ; -O1:    cmp w8, w0, uxth
-; -O1:    stlxrh w9, w1, [x2]
+; -O1:    stlxrh wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i16 %expected, i16 %new seq_cst seq_cst, align 2
     %r = extractvalue { i16, i1 } %pair, 0
     ret i16 %r
@@ -957,7 +957,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -987,7 +987,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1017,7 +1017,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new monotonic seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1047,7 +1047,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1077,7 +1077,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stxr w9, w1, [x2]
+; -O1:    stxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1107,7 +1107,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acquire seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1137,7 +1137,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_monotonic_weak:
 ; -O1:    ldxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1167,7 +1167,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1197,7 +1197,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new release seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1227,7 +1227,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1257,7 +1257,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1287,7 +1287,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new acq_rel seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1317,7 +1317,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst monotonic, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1347,7 +1347,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst acquire, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1377,7 +1377,7 @@
 ; -O1-LABEL: cmpxchg_i32_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr w8, [x2]
 ; -O1:    cmp w8, w0
-; -O1:    stlxr w9, w1, [x2]
+; -O1:    stlxr wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i32 %expected, i32 %new seq_cst seq_cst, align 4
     %r = extractvalue { i32, i1 } %pair, 0
     ret i32 %r
@@ -1407,7 +1407,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1437,7 +1437,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1467,7 +1467,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new monotonic seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1497,7 +1497,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1527,7 +1527,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stxr w9, x1, [x2]
+; -O1:    stxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1557,7 +1557,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acquire_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acquire seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1587,7 +1587,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_monotonic_weak:
 ; -O1:    ldxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1617,7 +1617,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1647,7 +1647,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_release_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new release seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1677,7 +1677,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1707,7 +1707,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1737,7 +1737,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new acq_rel seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1767,7 +1767,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst monotonic, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1797,7 +1797,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_acquire_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst acquire, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -1827,7 +1827,7 @@
 ; -O1-LABEL: cmpxchg_i64_aligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxr x8, [x2]
 ; -O1:    cmp x8, x0
-; -O1:    stlxr w9, x1, [x2]
+; -O1:    stlxr wzr, x1, [x2]
     %pair = cmpxchg weak ptr %ptr, i64 %expected, i64 %new seq_cst seq_cst, align 8
     %r = extractvalue { i64, i1 } %pair, 0
     ret i64 %r
@@ -2428,7 +2428,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2459,7 +2459,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2490,7 +2490,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_monotonic_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new monotonic seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2521,7 +2521,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2552,7 +2552,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stxrb w9, w1, [x2]
+; -O1:    stxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2583,7 +2583,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acquire_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acquire seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2614,7 +2614,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_monotonic_weak:
 ; -O1:    ldxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2645,7 +2645,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2676,7 +2676,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_release_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new release seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2707,7 +2707,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2738,7 +2738,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2769,7 +2769,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_acq_rel_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new acq_rel seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2800,7 +2800,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_monotonic_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst monotonic, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2831,7 +2831,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_acquire_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst acquire, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
@@ -2862,7 +2862,7 @@
 ; -O1-LABEL: cmpxchg_i8_unaligned_seq_cst_seq_cst_weak:
 ; -O1:    ldaxrb w8, [x2]
 ; -O1:    cmp w8, w0, uxtb
-; -O1:    stlxrb w9, w1, [x2]
+; -O1:    stlxrb wzr, w1, [x2]
     %pair = cmpxchg weak ptr %ptr, i8 %expected, i8 %new seq_cst seq_cst, align 1
     %r = extractvalue { i8, i1 } %pair, 0
     ret i8 %r
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-switch-bittest.ll b/llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-switch-bittest.ll
--- a/llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-switch-bittest.ll
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-switch-bittest.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
-; RUN: llc -mtriple aarch64 -aarch64-enable-atomic-cfg-tidy=0 -stop-after=irtranslator -global-isel -verify-machineinstrs %s -o - 2>&1 | FileCheck %s
+; RUN: llc -mtriple aarch64 -aarch64-enable-atomic-cfg-tidy=0 -stop-after=irtranslator -global-isel -verify-machineinstrs -disable-cgp-delete-phis %s -o - 2>&1 | FileCheck %s
 
 define i32 @test_bittest(i16 %p) {
   ; CHECK-LABEL: name: test_bittest
diff --git a/llvm/test/CodeGen/AArch64/machine_cse.ll b/llvm/test/CodeGen/AArch64/machine_cse.ll
--- a/llvm/test/CodeGen/AArch64/machine_cse.ll
+++ b/llvm/test/CodeGen/AArch64/machine_cse.ll
@@ -11,7 +11,7 @@
 @d = external global i32
 @e = external global i32
 
-define void @combine-sign-comparisons-by-cse(ptr %arg) {
+define i32 @combine-sign-comparisons-by-cse(ptr %arg) {
 ; CHECK: cmp
 ; CHECK: b.ge
 ; CHECK-NOT: cmp
@@ -45,7 +45,7 @@
 return:
   %retval.0 = phi i32 [ 0, %if.end ], [ 1, %land.lhs.true3 ], [ 1, %land.lhs.true ]
   store i32 %a, ptr %arg
-  ret void
+  ret i32 %retval.0
 }
 
 define void @combine_vector_zeros(ptr %p, ptr %q) {
diff --git a/llvm/test/CodeGen/Hexagon/autohvx/lower-insert-elt.ll b/llvm/test/CodeGen/Hexagon/autohvx/lower-insert-elt.ll
--- a/llvm/test/CodeGen/Hexagon/autohvx/lower-insert-elt.ll
+++ b/llvm/test/CodeGen/Hexagon/autohvx/lower-insert-elt.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon < %s | FileCheck %s
+; RUN: llc -march=hexagon -disable-cgp-delete-phis < %s | FileCheck %s
 ; REQUIRES: asserts
 
 ; Check that this testcase compiles successfully.
diff --git a/llvm/test/CodeGen/Hexagon/postinc-offset.ll b/llvm/test/CodeGen/Hexagon/postinc-offset.ll
--- a/llvm/test/CodeGen/Hexagon/postinc-offset.ll
+++ b/llvm/test/CodeGen/Hexagon/postinc-offset.ll
@@ -1,4 +1,4 @@
-; RUN: llc -enable-aa-sched-mi -march=hexagon -mcpu=hexagonv5 -rdf-opt=0 \
+; RUN: llc -enable-aa-sched-mi -march=hexagon -mcpu=hexagonv5 -rdf-opt=0 -disable-cgp-delete-phis \
 ; RUN:      < %s | FileCheck %s
 
 ; CHECK: {
diff --git a/llvm/test/CodeGen/Hexagon/swp-carried-1.ll b/llvm/test/CodeGen/Hexagon/swp-carried-1.ll
--- a/llvm/test/CodeGen/Hexagon/swp-carried-1.ll
+++ b/llvm/test/CodeGen/Hexagon/swp-carried-1.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -rdf-opt=0 -disable-hexagon-misched -hexagon-initial-cfg-cleanup=0 -lsr-setupcost-depth-limit=1 < %s -pipeliner-experimental-cg=true | FileCheck %s
+; RUN: llc -march=hexagon -rdf-opt=0 -disable-hexagon-misched -hexagon-initial-cfg-cleanup=0 -lsr-setupcost-depth-limit=1 -disable-cgp-delete-phis < %s -pipeliner-experimental-cg=true | FileCheck %s
 
 ; Test that we generate the correct code when a loop carried value
 ; is scheduled one stage earlier than it's use. The code in
diff --git a/llvm/test/CodeGen/Hexagon/swp-epilog-phi12.ll b/llvm/test/CodeGen/Hexagon/swp-epilog-phi12.ll
--- a/llvm/test/CodeGen/Hexagon/swp-epilog-phi12.ll
+++ b/llvm/test/CodeGen/Hexagon/swp-epilog-phi12.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -hexagon-initial-cfg-cleanup=0 -pipeliner-experimental-cg=true < %s | FileCheck %s
+; RUN: llc -march=hexagon -hexagon-initial-cfg-cleanup=0 -pipeliner-experimental-cg=true -disable-cgp-delete-phis < %s | FileCheck %s
 
 ; Test epilogue generation when reading loop-carried dependency from a previous
 ; stage. The first epilogue should read value from iteration N-1 of the kernel.
diff --git a/llvm/test/CodeGen/Hexagon/swp-epilog-phi6.ll b/llvm/test/CodeGen/Hexagon/swp-epilog-phi6.ll
--- a/llvm/test/CodeGen/Hexagon/swp-epilog-phi6.ll
+++ b/llvm/test/CodeGen/Hexagon/swp-epilog-phi6.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -O2 -debug-only=pipeliner -hexagon-initial-cfg-cleanup=0 < %s -o - 2>&1 > /dev/null | FileCheck %s
+; RUN: llc -march=hexagon -O2 -debug-only=pipeliner -hexagon-initial-cfg-cleanup=0 -disable-cgp-delete-phis < %s -o - 2>&1 > /dev/null | FileCheck %s
 ; REQUIRES: asserts
 
 ; Test that the phi in the first epilog block is getter the correct
diff --git a/llvm/test/CodeGen/Hexagon/swp-epilog-phi9.ll b/llvm/test/CodeGen/Hexagon/swp-epilog-phi9.ll
--- a/llvm/test/CodeGen/Hexagon/swp-epilog-phi9.ll
+++ b/llvm/test/CodeGen/Hexagon/swp-epilog-phi9.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -hexagon-initial-cfg-cleanup=0 < %s | FileCheck %s
+; RUN: llc -march=hexagon -hexagon-initial-cfg-cleanup=0 -disable-cgp-delete-phis < %s | FileCheck %s
 
 ; Test that we generate the correct Phi name in the last couple of epilog
 ; blocks, when there are 3 epilog blocks. The Phi was scheduled in stage
diff --git a/llvm/test/CodeGen/Hexagon/swp-lots-deps.ll b/llvm/test/CodeGen/Hexagon/swp-lots-deps.ll
--- a/llvm/test/CodeGen/Hexagon/swp-lots-deps.ll
+++ b/llvm/test/CodeGen/Hexagon/swp-lots-deps.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -enable-pipeliner -stats -o /dev/null < %s 2>&1 -pipeliner-experimental-cg=true | FileCheck %s --check-prefix=STATS
+; RUN: llc -march=hexagon -enable-pipeliner -stats -o /dev/null < %s 2>&1 -pipeliner-experimental-cg=true -disable-cgp-delete-phis | FileCheck %s --check-prefix=STATS
 ; REQUIRES: asserts
 
 ; STATS: 1 pipeliner        - Number of loops software pipelined
diff --git a/llvm/test/CodeGen/Hexagon/swp-prolog-phi.ll b/llvm/test/CodeGen/Hexagon/swp-prolog-phi.ll
--- a/llvm/test/CodeGen/Hexagon/swp-prolog-phi.ll
+++ b/llvm/test/CodeGen/Hexagon/swp-prolog-phi.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -rdf-opt=0 < %s -pipeliner-experimental-cg=true | FileCheck %s
+; RUN: llc -march=hexagon -rdf-opt=0 < %s -pipeliner-experimental-cg=true -disable-cgp-delete-phis | FileCheck %s
 
 ; Test that we generate the correct name for a value in a prolog block. The
 ; pipeliner was using an incorrect value for an instruction in the 2nd prolog
diff --git a/llvm/test/CodeGen/Hexagon/swp-tfri.ll b/llvm/test/CodeGen/Hexagon/swp-tfri.ll
--- a/llvm/test/CodeGen/Hexagon/swp-tfri.ll
+++ b/llvm/test/CodeGen/Hexagon/swp-tfri.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -enable-pipeliner -hexagon-initial-cfg-cleanup=0 -stats -o /dev/null < %s 2>&1 -pipeliner-experimental-cg=true | FileCheck %s --check-prefix=STATS
+; RUN: llc -march=hexagon -enable-pipeliner -hexagon-initial-cfg-cleanup=0 -stats -o /dev/null < %s 2>&1 -pipeliner-experimental-cg=true -disable-cgp-delete-phis | FileCheck %s --check-prefix=STATS
 ; REQUIRES: asserts
 
 ; Check that we handle the case when a value is first defined in the loop.
diff --git a/llvm/test/CodeGen/Hexagon/v6-unaligned-spill.ll b/llvm/test/CodeGen/Hexagon/v6-unaligned-spill.ll
--- a/llvm/test/CodeGen/Hexagon/v6-unaligned-spill.ll
+++ b/llvm/test/CodeGen/Hexagon/v6-unaligned-spill.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon < %s | FileCheck %s
+; RUN: llc -march=hexagon -disable-cgp-delete-phis < %s | FileCheck %s
 
 ; Test that we no longer generate an unaligned vector store for a spill when
 ; a function has an alloca.
diff --git a/llvm/test/CodeGen/PowerPC/sink-side-effect.ll b/llvm/test/CodeGen/PowerPC/sink-side-effect.ll
--- a/llvm/test/CodeGen/PowerPC/sink-side-effect.ll
+++ b/llvm/test/CodeGen/PowerPC/sink-side-effect.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=powerpc64le -mcpu=pwr9 -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple=powerpc64le -mcpu=pwr9 -verify-machineinstrs -disable-cgp-delete-phis < %s | FileCheck %s
 
 define double @zot(ptr %arg, ptr %arg1, ptr %arg2) {
 ; CHECK-LABEL: zot:
diff --git a/llvm/test/CodeGen/PowerPC/sms-iterator.ll b/llvm/test/CodeGen/PowerPC/sms-iterator.ll
--- a/llvm/test/CodeGen/PowerPC/sms-iterator.ll
+++ b/llvm/test/CodeGen/PowerPC/sms-iterator.ll
@@ -1,6 +1,6 @@
 ; REQUIRES: asserts
 ; RUN: llc < %s -mtriple=powerpc64le-unknown-linux-gnu -verify-machineinstrs\
-; RUN:       -mcpu=pwr9 --ppc-enable-pipeliner -debug-only=pipeliner 2>&1 \
+; RUN:       -mcpu=pwr9 --ppc-enable-pipeliner -debug-only=pipeliner -disable-cgp-delete-phis 2>&1 \
 ; RUN:       >/dev/null | FileCheck %s
 
 %0 = type { i32, [16 x double] }
diff --git a/llvm/test/CodeGen/Thumb2/2011-06-07-TwoAddrEarlyClobber.ll b/llvm/test/CodeGen/Thumb2/2011-06-07-TwoAddrEarlyClobber.ll
--- a/llvm/test/CodeGen/Thumb2/2011-06-07-TwoAddrEarlyClobber.ll
+++ b/llvm/test/CodeGen/Thumb2/2011-06-07-TwoAddrEarlyClobber.ll
@@ -1,4 +1,4 @@
-; RUN: llc -mtriple=thumbv7-apple-darwin10 -arm-atomic-cfg-tidy=0 < %s | FileCheck %s
+; RUN: llc -mtriple=thumbv7-apple-darwin10 -arm-atomic-cfg-tidy=0 -disable-cgp-delete-phis < %s | FileCheck %s
 
 %struct.op = type { ptr, ptr, ptr, i32, i16, i16, i8, i8 }
 
diff --git a/llvm/test/CodeGen/X86/2007-01-13-StackPtrIndex.ll b/llvm/test/CodeGen/X86/2007-01-13-StackPtrIndex.ll
--- a/llvm/test/CodeGen/X86/2007-01-13-StackPtrIndex.ll
+++ b/llvm/test/CodeGen/X86/2007-01-13-StackPtrIndex.ll
@@ -59,20 +59,20 @@
 ; CHECK-NEXT:    je .LBB0_10
 ; CHECK-NEXT:  .LBB0_3: # %a29b173
 ; CHECK-NEXT:    # =>This Loop Header: Depth=1
-; CHECK-NEXT:    # Child Loop BB0_37 Depth 2
+; CHECK-NEXT:    # Child Loop BB0_36 Depth 2
 ; CHECK-NEXT:    # Child Loop BB0_19 Depth 2
 ; CHECK-NEXT:    # Child Loop BB0_20 Depth 2
-; CHECK-NEXT:    # Child Loop BB0_21 Depth 3
-; CHECK-NEXT:    # Child Loop BB0_23 Depth 2
-; CHECK-NEXT:    # Child Loop BB0_24 Depth 3
-; CHECK-NEXT:    # Child Loop BB0_26 Depth 2
+; CHECK-NEXT:    # Child Loop BB0_37 Depth 3
+; CHECK-NEXT:    # Child Loop BB0_22 Depth 2
+; CHECK-NEXT:    # Child Loop BB0_23 Depth 3
+; CHECK-NEXT:    # Child Loop BB0_25 Depth 2
 ; CHECK-NEXT:    # Child Loop BB0_38 Depth 3
-; CHECK-NEXT:    # Child Loop BB0_29 Depth 3
-; CHECK-NEXT:    # Child Loop BB0_30 Depth 2
+; CHECK-NEXT:    # Child Loop BB0_28 Depth 3
+; CHECK-NEXT:    # Child Loop BB0_29 Depth 2
 ; CHECK-NEXT:    # Child Loop BB0_39 Depth 3
-; CHECK-NEXT:    # Child Loop BB0_33 Depth 3
-; CHECK-NEXT:    # Child Loop BB0_34 Depth 2
-; CHECK-NEXT:    # Child Loop BB0_36 Depth 2
+; CHECK-NEXT:    # Child Loop BB0_32 Depth 3
+; CHECK-NEXT:    # Child Loop BB0_33 Depth 2
+; CHECK-NEXT:    # Child Loop BB0_35 Depth 2
 ; CHECK-NEXT:    testl %eax, %eax
 ; CHECK-NEXT:    js .LBB0_4
 ; CHECK-NEXT:  # %bb.17: # %b179
@@ -80,11 +80,11 @@
 ; CHECK-NEXT:    testq %rdx, %rdx
 ; CHECK-NEXT:    js .LBB0_18
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_37: # %a30b
+; CHECK-NEXT:  .LBB0_36: # %a30b
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=2
 ; CHECK-NEXT:    testb %dil, %dil
-; CHECK-NEXT:    je .LBB0_37
+; CHECK-NEXT:    je .LBB0_36
 ; CHECK-NEXT:  .LBB0_18: # %b188
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
 ; CHECK-NEXT:    testb %r8b, %r8b
@@ -104,33 +104,33 @@
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
 ; CHECK-NEXT:    movl %eax, %r10d
 ; CHECK-NEXT:    orl %esi, %r10d
-; CHECK-NEXT:    jns .LBB0_26
+; CHECK-NEXT:    jns .LBB0_25
 ; CHECK-NEXT:  .LBB0_6: # %a57b
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
 ; CHECK-NEXT:    shrl $31, %r9d
 ; CHECK-NEXT:    testb %r9b, %r9b
-; CHECK-NEXT:    je .LBB0_30
+; CHECK-NEXT:    je .LBB0_29
 ; CHECK-NEXT:  .LBB0_7: # %a66b
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
 ; CHECK-NEXT:    shrl $31, %r10d
 ; CHECK-NEXT:    testb %r10b, %r10b
 ; CHECK-NEXT:    jne .LBB0_8
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_34: # %a74b
+; CHECK-NEXT:  .LBB0_33: # %a74b
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=2
 ; CHECK-NEXT:    testb %dil, %dil
-; CHECK-NEXT:    jne .LBB0_34
-; CHECK-NEXT:  # %bb.35: # %b1582
-; CHECK-NEXT:    # in Loop: Header=BB0_34 Depth=2
+; CHECK-NEXT:    jne .LBB0_33
+; CHECK-NEXT:  # %bb.34: # %b1582
+; CHECK-NEXT:    # in Loop: Header=BB0_33 Depth=2
 ; CHECK-NEXT:    testb %dil, %dil
-; CHECK-NEXT:    jne .LBB0_34
+; CHECK-NEXT:    jne .LBB0_33
 ; CHECK-NEXT:  .LBB0_8: # %a93b
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
 ; CHECK-NEXT:    testl %eax, %eax
 ; CHECK-NEXT:    js .LBB0_9
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_36: # %a97b
+; CHECK-NEXT:  .LBB0_35: # %a97b
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=2
 ; CHECK-NEXT:    movss {{.*#+}} xmm1 = mem[0],zero,zero,zero
@@ -141,108 +141,108 @@
 ; CHECK-NEXT:    addss %xmm1, %xmm2
 ; CHECK-NEXT:    movss %xmm2, i6000(%rip)
 ; CHECK-NEXT:    testb %dil, %dil
-; CHECK-NEXT:    jne .LBB0_36
+; CHECK-NEXT:    jne .LBB0_35
 ; CHECK-NEXT:    jmp .LBB0_9
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_22: # %b463
+; CHECK-NEXT:  .LBB0_21: # %b377
 ; CHECK-NEXT:    # in Loop: Header=BB0_20 Depth=2
 ; CHECK-NEXT:    testb %dil, %dil
-; CHECK-NEXT:    je .LBB0_23
+; CHECK-NEXT:    je .LBB0_22
 ; CHECK-NEXT:  .LBB0_20: # %b341
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
 ; CHECK-NEXT:    # => This Loop Header: Depth=2
-; CHECK-NEXT:    # Child Loop BB0_21 Depth 3
+; CHECK-NEXT:    # Child Loop BB0_37 Depth 3
 ; CHECK-NEXT:    testq %rsi, %rsi
-; CHECK-NEXT:    js .LBB0_22
+; CHECK-NEXT:    js .LBB0_21
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_21: # %a35b
+; CHECK-NEXT:  .LBB0_37: # %a35b
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
 ; CHECK-NEXT:    # Parent Loop BB0_20 Depth=2
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=3
 ; CHECK-NEXT:    testb %dil, %dil
-; CHECK-NEXT:    je .LBB0_21
-; CHECK-NEXT:    jmp .LBB0_22
+; CHECK-NEXT:    je .LBB0_37
+; CHECK-NEXT:    jmp .LBB0_21
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_28: # %b1016
-; CHECK-NEXT:    # in Loop: Header=BB0_26 Depth=2
+; CHECK-NEXT:  .LBB0_27: # %b1016
+; CHECK-NEXT:    # in Loop: Header=BB0_25 Depth=2
 ; CHECK-NEXT:    testq %rsi, %rsi
 ; CHECK-NEXT:    jle .LBB0_6
-; CHECK-NEXT:  .LBB0_26: # %b858
+; CHECK-NEXT:  .LBB0_25: # %b858
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
 ; CHECK-NEXT:    # => This Loop Header: Depth=2
 ; CHECK-NEXT:    # Child Loop BB0_38 Depth 3
-; CHECK-NEXT:    # Child Loop BB0_29 Depth 3
+; CHECK-NEXT:    # Child Loop BB0_28 Depth 3
 ; CHECK-NEXT:    testq %rdx, %rdx
-; CHECK-NEXT:    js .LBB0_27
+; CHECK-NEXT:    js .LBB0_26
 ; CHECK-NEXT:    .p2align 4, 0x90
 ; CHECK-NEXT:  .LBB0_38: # %a53b
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
-; CHECK-NEXT:    # Parent Loop BB0_26 Depth=2
+; CHECK-NEXT:    # Parent Loop BB0_25 Depth=2
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=3
 ; CHECK-NEXT:    testb %dil, %dil
 ; CHECK-NEXT:    je .LBB0_38
-; CHECK-NEXT:  .LBB0_27: # %b879
-; CHECK-NEXT:    # in Loop: Header=BB0_26 Depth=2
+; CHECK-NEXT:  .LBB0_26: # %b879
+; CHECK-NEXT:    # in Loop: Header=BB0_25 Depth=2
 ; CHECK-NEXT:    testb %r8b, %r8b
-; CHECK-NEXT:    jne .LBB0_28
+; CHECK-NEXT:    jne .LBB0_27
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_29: # %a53b1019
+; CHECK-NEXT:  .LBB0_28: # %a53b1019
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
-; CHECK-NEXT:    # Parent Loop BB0_26 Depth=2
+; CHECK-NEXT:    # Parent Loop BB0_25 Depth=2
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=3
 ; CHECK-NEXT:    testq %rdx, %rdx
-; CHECK-NEXT:    jle .LBB0_29
-; CHECK-NEXT:    jmp .LBB0_28
+; CHECK-NEXT:    jle .LBB0_28
+; CHECK-NEXT:    jmp .LBB0_27
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_32: # %b1263
-; CHECK-NEXT:    # in Loop: Header=BB0_30 Depth=2
+; CHECK-NEXT:  .LBB0_31: # %b1263
+; CHECK-NEXT:    # in Loop: Header=BB0_29 Depth=2
 ; CHECK-NEXT:    testq %rdx, %rdx
 ; CHECK-NEXT:    jle .LBB0_7
-; CHECK-NEXT:  .LBB0_30: # %b1117
+; CHECK-NEXT:  .LBB0_29: # %b1117
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
 ; CHECK-NEXT:    # => This Loop Header: Depth=2
 ; CHECK-NEXT:    # Child Loop BB0_39 Depth 3
-; CHECK-NEXT:    # Child Loop BB0_33 Depth 3
+; CHECK-NEXT:    # Child Loop BB0_32 Depth 3
 ; CHECK-NEXT:    testq %rsi, %rsi
-; CHECK-NEXT:    js .LBB0_31
+; CHECK-NEXT:    js .LBB0_30
 ; CHECK-NEXT:    .p2align 4, 0x90
 ; CHECK-NEXT:  .LBB0_39: # %a63b
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
-; CHECK-NEXT:    # Parent Loop BB0_30 Depth=2
+; CHECK-NEXT:    # Parent Loop BB0_29 Depth=2
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=3
 ; CHECK-NEXT:    testq %rsi, %rsi
 ; CHECK-NEXT:    jle .LBB0_39
-; CHECK-NEXT:  .LBB0_31: # %b1139
-; CHECK-NEXT:    # in Loop: Header=BB0_30 Depth=2
+; CHECK-NEXT:  .LBB0_30: # %b1139
+; CHECK-NEXT:    # in Loop: Header=BB0_29 Depth=2
 ; CHECK-NEXT:    testq %rsi, %rsi
-; CHECK-NEXT:    jle .LBB0_32
+; CHECK-NEXT:    jle .LBB0_31
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_33: # %a63b1266
+; CHECK-NEXT:  .LBB0_32: # %a63b1266
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
-; CHECK-NEXT:    # Parent Loop BB0_30 Depth=2
+; CHECK-NEXT:    # Parent Loop BB0_29 Depth=2
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=3
 ; CHECK-NEXT:    testq %rsi, %rsi
-; CHECK-NEXT:    jle .LBB0_33
-; CHECK-NEXT:    jmp .LBB0_32
+; CHECK-NEXT:    jle .LBB0_32
+; CHECK-NEXT:    jmp .LBB0_31
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_25: # %b712
-; CHECK-NEXT:    # in Loop: Header=BB0_23 Depth=2
+; CHECK-NEXT:  .LBB0_24: # %b712
+; CHECK-NEXT:    # in Loop: Header=BB0_22 Depth=2
 ; CHECK-NEXT:    testb %dil, %dil
 ; CHECK-NEXT:    je .LBB0_5
-; CHECK-NEXT:  .LBB0_23: # %b535
+; CHECK-NEXT:  .LBB0_22: # %b535
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
 ; CHECK-NEXT:    # => This Loop Header: Depth=2
-; CHECK-NEXT:    # Child Loop BB0_24 Depth 3
+; CHECK-NEXT:    # Child Loop BB0_23 Depth 3
 ; CHECK-NEXT:    testq %rdx, %rdx
-; CHECK-NEXT:    js .LBB0_25
+; CHECK-NEXT:    js .LBB0_24
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB0_24: # %a45b
+; CHECK-NEXT:  .LBB0_23: # %a45b
 ; CHECK-NEXT:    # Parent Loop BB0_3 Depth=1
-; CHECK-NEXT:    # Parent Loop BB0_23 Depth=2
+; CHECK-NEXT:    # Parent Loop BB0_22 Depth=2
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=3
 ; CHECK-NEXT:    testb %dil, %dil
-; CHECK-NEXT:    je .LBB0_24
-; CHECK-NEXT:    jmp .LBB0_25
+; CHECK-NEXT:    je .LBB0_23
+; CHECK-NEXT:    jmp .LBB0_24
 ; CHECK-NEXT:  .LBB0_10: # %a109b
 ; CHECK-NEXT:    movq %rbp, %rsp
 ; CHECK-NEXT:    popq %rbp
diff --git a/llvm/test/CodeGen/X86/2008-04-28-CoalescerBug.ll b/llvm/test/CodeGen/X86/2008-04-28-CoalescerBug.ll
--- a/llvm/test/CodeGen/X86/2008-04-28-CoalescerBug.ll
+++ b/llvm/test/CodeGen/X86/2008-04-28-CoalescerBug.ll
@@ -46,7 +46,6 @@
 ; CHECK-NEXT:    je LBB0_4
 ; CHECK-NEXT:  ## %bb.8: ## %bb13236
 ; CHECK-NEXT:    ## in Loop: Header=BB0_4 Depth=1
-; CHECK-NEXT:    cmpw $-1, %cx
 ; CHECK-NEXT:    testb %al, %al
 ; CHECK-NEXT:    jne LBB0_4
 ; CHECK-NEXT:  ## %bb.9: ## %bb13572
diff --git a/llvm/test/CodeGen/X86/avx512-i1test.ll b/llvm/test/CodeGen/X86/avx512-i1test.ll
--- a/llvm/test/CodeGen/X86/avx512-i1test.ll
+++ b/llvm/test/CodeGen/X86/avx512-i1test.ll
@@ -1,6 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -mattr=+avx512f | FileCheck %s
-; RUN: llc < %s -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq | FileCheck %s
+; RUN: llc < %s -mattr=+avx512f -disable-cgp-delete-phis | FileCheck %s
+; RUN: llc < %s -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -disable-cgp-delete-phis | FileCheck %s
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/CodeGen/X86/ins_subreg_coalesce-3.ll b/llvm/test/CodeGen/X86/ins_subreg_coalesce-3.ll
--- a/llvm/test/CodeGen/X86/ins_subreg_coalesce-3.ll
+++ b/llvm/test/CodeGen/X86/ins_subreg_coalesce-3.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -mtriple=x86_64-- | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-- -disable-cgp-delete-phis | FileCheck %s
 
 	%struct.COMPOSITE = type { i8, i16, i16 }
 	%struct.FILE = type { ptr, i32, i32, i16, i16, %struct.__sbuf, i32, ptr, ptr, ptr, ptr, ptr, %struct.__sbuf, ptr, i32, [3 x i8], [1 x i8], %struct.__sbuf, i32, i64 }
diff --git a/llvm/test/CodeGen/X86/masked_store.ll b/llvm/test/CodeGen/X86/masked_store.ll
--- a/llvm/test/CodeGen/X86/masked_store.ll
+++ b/llvm/test/CodeGen/X86/masked_store.ll
@@ -6268,26 +6268,15 @@
 ; From https://reviews.llvm.org/rGf8d9097168b7#1165311
 define void @undefshuffle(<8 x i1> %i0, ptr %src, ptr %dst) #0 {
 ; SSE2-LABEL: undefshuffle:
-; SSE2:       ## %bb.0:
+; SSE2:       ## %bb.0: ## %else
 ; SSE2-NEXT:    movaps %xmm0, -{{[0-9]+}}(%rsp)
-; SSE2-NEXT:    movb $1, %al
-; SSE2-NEXT:    testb %al, %al
-; SSE2-NEXT:    testb %al, %al
-; SSE2-NEXT:    testb %al, %al
-; SSE2-NEXT:    movzbl -{{[0-9]+}}(%rsp), %ecx
-; SSE2-NEXT:    testb %al, %al
-; SSE2-NEXT:    movd %ecx, %xmm0
-; SSE2-NEXT:    movzbl -{{[0-9]+}}(%rsp), %ecx
-; SSE2-NEXT:    testb %al, %al
-; SSE2-NEXT:    pinsrw $1, %ecx, %xmm0
-; SSE2-NEXT:    movl -{{[0-9]+}}(%rsp), %ecx
-; SSE2-NEXT:    testb %al, %al
-; SSE2-NEXT:    pinsrw $2, %ecx, %xmm0
 ; SSE2-NEXT:    movzbl -{{[0-9]+}}(%rsp), %eax
-; SSE2-NEXT:    movb $1, %cl
-; SSE2-NEXT:    testb %cl, %cl
+; SSE2-NEXT:    movd %eax, %xmm0
+; SSE2-NEXT:    movzbl -{{[0-9]+}}(%rsp), %eax
+; SSE2-NEXT:    pinsrw $1, %eax, %xmm0
+; SSE2-NEXT:    pinsrw $2, -{{[0-9]+}}(%rsp), %xmm0
+; SSE2-NEXT:    movzbl -{{[0-9]+}}(%rsp), %eax
 ; SSE2-NEXT:    pinsrw $3, %eax, %xmm0
-; SSE2-NEXT:    testb %cl, %cl
 ; SSE2-NEXT:    psllw $15, %xmm0
 ; SSE2-NEXT:    packsswb %xmm0, %xmm0
 ; SSE2-NEXT:    pmovmskb %xmm0, %eax
@@ -6349,18 +6338,9 @@
 ; SSE2-NEXT:    retq
 ;
 ; SSE4-LABEL: undefshuffle:
-; SSE4:       ## %bb.0:
-; SSE4-NEXT:    movb $1, %al
-; SSE4-NEXT:    testb %al, %al
-; SSE4-NEXT:    testb %al, %al
-; SSE4-NEXT:    testb %al, %al
-; SSE4-NEXT:    testb %al, %al
-; SSE4-NEXT:    testb %al, %al
-; SSE4-NEXT:    testb %al, %al
-; SSE4-NEXT:    testb %al, %al
-; SSE4-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
-; SSE4-NEXT:    testb %al, %al
+; SSE4:       ## %bb.0: ## %else
 ; SSE4-NEXT:    psllw $15, %xmm0
+; SSE4-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
 ; SSE4-NEXT:    packsswb %xmm0, %xmm0
 ; SSE4-NEXT:    pmovmskb %xmm0, %eax
 ; SSE4-NEXT:    testb $1, %al
diff --git a/llvm/test/CodeGen/X86/pr49451.ll b/llvm/test/CodeGen/X86/pr49451.ll
--- a/llvm/test/CodeGen/X86/pr49451.ll
+++ b/llvm/test/CodeGen/X86/pr49451.ll
@@ -22,7 +22,6 @@
 ; X86-NEXT:    je .LBB0_2
 ; X86-NEXT:  # %bb.3: # %if.end1401
 ; X86-NEXT:    # in Loop: Header=BB0_1 Depth=1
-; X86-NEXT:    testb %dl, %dl
 ; X86-NEXT:    addl %eax, %esi
 ; X86-NEXT:    movw %si, s_2
 ; X86-NEXT:    movw %bx, s_0
@@ -45,7 +44,6 @@
 ; X64-NEXT:    je .LBB0_2
 ; X64-NEXT:  # %bb.3: # %if.end1401
 ; X64-NEXT:    # in Loop: Header=BB0_1 Depth=1
-; X64-NEXT:    testb %cl, %cl
 ; X64-NEXT:    addl %esi, %edx
 ; X64-NEXT:    movw %dx, s_2(%rip)
 ; X64-NEXT:    leal -23090(%rax), %edi
diff --git a/llvm/test/CodeGen/X86/pr53990-incorrect-machine-sink.ll b/llvm/test/CodeGen/X86/pr53990-incorrect-machine-sink.ll
--- a/llvm/test/CodeGen/X86/pr53990-incorrect-machine-sink.ll
+++ b/llvm/test/CodeGen/X86/pr53990-incorrect-machine-sink.ll
@@ -7,24 +7,31 @@
 ; CHECK-LABEL: test:
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:    pushq %rbp
+; CHECK-NEXT:    pushq %r15
 ; CHECK-NEXT:    pushq %r14
 ; CHECK-NEXT:    pushq %rbx
+; CHECK-NEXT:    pushq %rax
 ; CHECK-NEXT:    movq %rdx, %rbx
 ; CHECK-NEXT:    movl %edi, %ebp
 ; CHECK-NEXT:    movq (%rsi), %r14
-; CHECK-NEXT:    xorl %eax, %eax
-; CHECK-NEXT:    jmpq *.LJTI0_0(,%rax,8)
-; CHECK-NEXT:  .LBB0_1: # %split.3
-; CHECK-NEXT:    testb $1, %bpl
-; CHECK-NEXT:    je .LBB0_3
-; CHECK-NEXT:  # %bb.2: # %clobber
-; CHECK-NEXT:    callq clobber@PLT
-; CHECK-NEXT:  .LBB0_3: # %sink
+; CHECK-NEXT:    movb $1, %r15b
+; CHECK-NEXT:    jmp .LBB0_1
+; CHECK-NEXT:    .p2align 4, 0x90
+; CHECK-NEXT:  .LBB0_4: # %sink
+; CHECK-NEXT:    # in Loop: Header=BB0_1 Depth=1
 ; CHECK-NEXT:    movq %r14, (%rbx)
-; CHECK-NEXT:  .LBB0_4: # %latch
+; CHECK-NEXT:  .LBB0_1: # %loop
 ; CHECK-NEXT:    # =>This Inner Loop Header: Depth=1
-; CHECK-NEXT:    xorl %eax, %eax
-; CHECK-NEXT:    jmpq *.LJTI0_0(,%rax,8)
+; CHECK-NEXT:    testb %r15b, %r15b
+; CHECK-NEXT:    jne .LBB0_1
+; CHECK-NEXT:  # %bb.2: # %split.3
+; CHECK-NEXT:    # in Loop: Header=BB0_1 Depth=1
+; CHECK-NEXT:    testb $1, %bpl
+; CHECK-NEXT:    je .LBB0_4
+; CHECK-NEXT:  # %bb.3: # %clobber
+; CHECK-NEXT:    # in Loop: Header=BB0_1 Depth=1
+; CHECK-NEXT:    callq clobber@PLT
+; CHECK-NEXT:    jmp .LBB0_4
 entry:
   %val = load i64, ptr %p, align 8
   br label %loop
diff --git a/llvm/test/CodeGen/X86/tail-dup-merge-loop-headers.ll b/llvm/test/CodeGen/X86/tail-dup-merge-loop-headers.ll
--- a/llvm/test/CodeGen/X86/tail-dup-merge-loop-headers.ll
+++ b/llvm/test/CodeGen/X86/tail-dup-merge-loop-headers.ll
@@ -98,7 +98,7 @@
 ; CHECK-NEXT:    movl $1, %ebx
 ; CHECK-NEXT:    xorl %eax, %eax
 ; CHECK-NEXT:    testb %al, %al
-; CHECK-NEXT:    jne .LBB1_27
+; CHECK-NEXT:    jne .LBB1_24
 ; CHECK-NEXT:  # %bb.1: # %if.end19
 ; CHECK-NEXT:    movl %esi, %ebp
 ; CHECK-NEXT:    movq %rdi, %r15
@@ -109,106 +109,87 @@
 ; CHECK-NEXT:    movq %r12, %rdi
 ; CHECK-NEXT:    callq cli_calloc@PLT
 ; CHECK-NEXT:    testl %ebp, %ebp
-; CHECK-NEXT:    je .LBB1_26
+; CHECK-NEXT:    je .LBB1_23
 ; CHECK-NEXT:  # %bb.2: # %if.end19
 ; CHECK-NEXT:    testl %r13d, %r13d
-; CHECK-NEXT:    je .LBB1_26
+; CHECK-NEXT:    je .LBB1_23
 ; CHECK-NEXT:  # %bb.3: # %if.end19
 ; CHECK-NEXT:    movq %rax, %r14
 ; CHECK-NEXT:    xorl %eax, %eax
 ; CHECK-NEXT:    testb %al, %al
-; CHECK-NEXT:    jne .LBB1_26
+; CHECK-NEXT:    jne .LBB1_23
 ; CHECK-NEXT:  # %bb.4: # %if.end19
 ; CHECK-NEXT:    cmpq %r15, %r14
-; CHECK-NEXT:    jb .LBB1_26
+; CHECK-NEXT:    jb .LBB1_23
 ; CHECK-NEXT:  # %bb.5: # %if.end50
 ; CHECK-NEXT:    movq %r14, %rdi
 ; CHECK-NEXT:    movq %r12, %rdx
 ; CHECK-NEXT:    callq memcpy@PLT
 ; CHECK-NEXT:    cmpl $4, %ebx
-; CHECK-NEXT:    jb .LBB1_29
+; CHECK-NEXT:    jb .LBB1_26
 ; CHECK-NEXT:  # %bb.6: # %shared_preheader
-; CHECK-NEXT:    movb $32, %dl
+; CHECK-NEXT:    movb $32, %cl
 ; CHECK-NEXT:    xorl %eax, %eax
-; CHECK-NEXT:    # implicit-def: $rcx
-; CHECK-NEXT:    jmp .LBB1_9
+; CHECK-NEXT:    jmp .LBB1_8
 ; CHECK-NEXT:    .p2align 4, 0x90
 ; CHECK-NEXT:  .LBB1_7: # %merge_predecessor_split
-; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=1
-; CHECK-NEXT:    movb $32, %dl
-; CHECK-NEXT:    xorl %esi, %esi
-; CHECK-NEXT:  .LBB1_8: # %outer_loop_latch
-; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=1
-; CHECK-NEXT:    movzwl %si, %esi
-; CHECK-NEXT:    decl %esi
-; CHECK-NEXT:    movzwl %si, %esi
-; CHECK-NEXT:    leaq 1(%rcx,%rsi), %rcx
-; CHECK-NEXT:  .LBB1_9: # %outer_loop_header
+; CHECK-NEXT:    # in Loop: Header=BB1_8 Depth=1
+; CHECK-NEXT:    movb $32, %cl
+; CHECK-NEXT:  .LBB1_8: # %outer_loop_header
 ; CHECK-NEXT:    # =>This Loop Header: Depth=1
-; CHECK-NEXT:    # Child Loop BB1_10 Depth 2
+; CHECK-NEXT:    # Child Loop BB1_9 Depth 2
 ; CHECK-NEXT:    testl %r13d, %r13d
-; CHECK-NEXT:    je .LBB1_19
+; CHECK-NEXT:    je .LBB1_16
 ; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB1_10: # %shared_loop_header
-; CHECK-NEXT:    # Parent Loop BB1_9 Depth=1
+; CHECK-NEXT:  .LBB1_9: # %shared_loop_header
+; CHECK-NEXT:    # Parent Loop BB1_8 Depth=1
 ; CHECK-NEXT:    # => This Inner Loop Header: Depth=2
 ; CHECK-NEXT:    testq %r14, %r14
-; CHECK-NEXT:    jne .LBB1_28
-; CHECK-NEXT:  # %bb.11: # %inner_loop_body
-; CHECK-NEXT:    # in Loop: Header=BB1_10 Depth=2
+; CHECK-NEXT:    jne .LBB1_25
+; CHECK-NEXT:  # %bb.10: # %inner_loop_body
+; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=2
 ; CHECK-NEXT:    testl %eax, %eax
-; CHECK-NEXT:    jns .LBB1_10
-; CHECK-NEXT:  # %bb.12: # %if.end96.i
-; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=1
+; CHECK-NEXT:    jns .LBB1_9
+; CHECK-NEXT:  # %bb.11: # %if.end96.i
+; CHECK-NEXT:    # in Loop: Header=BB1_8 Depth=1
 ; CHECK-NEXT:    cmpl $3, %r13d
-; CHECK-NEXT:    jae .LBB1_23
-; CHECK-NEXT:  # %bb.13: # %if.end287.i
-; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=1
-; CHECK-NEXT:    xorl %esi, %esi
-; CHECK-NEXT:    cmpl $1, %r13d
-; CHECK-NEXT:    setne %dl
+; CHECK-NEXT:    jae .LBB1_20
+; CHECK-NEXT:  # %bb.12: # %if.end287.i
+; CHECK-NEXT:    # in Loop: Header=BB1_8 Depth=1
 ; CHECK-NEXT:    testb %al, %al
-; CHECK-NEXT:    jne .LBB1_17
-; CHECK-NEXT:  # %bb.14: # %if.end308.i
-; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=1
+; CHECK-NEXT:    # implicit-def: $cl
+; CHECK-NEXT:    jne .LBB1_8
+; CHECK-NEXT:  # %bb.13: # %if.end308.i
+; CHECK-NEXT:    # in Loop: Header=BB1_8 Depth=1
 ; CHECK-NEXT:    testb %al, %al
 ; CHECK-NEXT:    je .LBB1_7
-; CHECK-NEXT:  # %bb.15: # %if.end335.i
-; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=1
-; CHECK-NEXT:    xorl %edx, %edx
-; CHECK-NEXT:    testb %dl, %dl
-; CHECK-NEXT:    movl $0, %esi
+; CHECK-NEXT:  # %bb.14: # %if.end335.i
+; CHECK-NEXT:    # in Loop: Header=BB1_8 Depth=1
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    testb %cl, %cl
 ; CHECK-NEXT:    jne .LBB1_8
-; CHECK-NEXT:  # %bb.16: # %merge_other
-; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=1
-; CHECK-NEXT:    xorl %esi, %esi
-; CHECK-NEXT:    jmp .LBB1_18
-; CHECK-NEXT:    .p2align 4, 0x90
-; CHECK-NEXT:  .LBB1_17: # in Loop: Header=BB1_9 Depth=1
-; CHECK-NEXT:    movb %dl, %sil
-; CHECK-NEXT:    addl $3, %esi
-; CHECK-NEXT:  .LBB1_18: # %outer_loop_latch
-; CHECK-NEXT:    # in Loop: Header=BB1_9 Depth=1
-; CHECK-NEXT:    # implicit-def: $dl
+; CHECK-NEXT:  # %bb.15: # %merge_other
+; CHECK-NEXT:    # in Loop: Header=BB1_8 Depth=1
+; CHECK-NEXT:    # implicit-def: $cl
 ; CHECK-NEXT:    jmp .LBB1_8
-; CHECK-NEXT:  .LBB1_26:
+; CHECK-NEXT:  .LBB1_23:
 ; CHECK-NEXT:    movl $1, %ebx
-; CHECK-NEXT:    jmp .LBB1_27
-; CHECK-NEXT:  .LBB1_19: # %while.cond.us1412.i
+; CHECK-NEXT:    jmp .LBB1_24
+; CHECK-NEXT:  .LBB1_16: # %while.cond.us1412.i
 ; CHECK-NEXT:    xorl %eax, %eax
 ; CHECK-NEXT:    testb %al, %al
 ; CHECK-NEXT:    movl $1, %ebx
-; CHECK-NEXT:    jne .LBB1_21
-; CHECK-NEXT:  # %bb.20: # %while.cond.us1412.i
-; CHECK-NEXT:    decb %dl
-; CHECK-NEXT:    jne .LBB1_27
-; CHECK-NEXT:  .LBB1_21: # %if.end41.us1436.i
-; CHECK-NEXT:  .LBB1_23: # %if.then99.i
+; CHECK-NEXT:    jne .LBB1_18
+; CHECK-NEXT:  # %bb.17: # %while.cond.us1412.i
+; CHECK-NEXT:    decb %cl
+; CHECK-NEXT:    jne .LBB1_24
+; CHECK-NEXT:  .LBB1_18: # %if.end41.us1436.i
+; CHECK-NEXT:  .LBB1_20: # %if.then99.i
 ; CHECK-NEXT:    movq .str.6@GOTPCREL(%rip), %rdi
 ; CHECK-NEXT:    xorl %ebx, %ebx
 ; CHECK-NEXT:    xorl %eax, %eax
 ; CHECK-NEXT:    callq cli_dbgmsg@PLT
-; CHECK-NEXT:  .LBB1_27: # %cleanup
+; CHECK-NEXT:  .LBB1_24: # %cleanup
 ; CHECK-NEXT:    movl %ebx, %eax
 ; CHECK-NEXT:    addq $8, %rsp
 ; CHECK-NEXT:    popq %rbx
@@ -218,8 +199,8 @@
 ; CHECK-NEXT:    popq %r15
 ; CHECK-NEXT:    popq %rbp
 ; CHECK-NEXT:    retq
-; CHECK-NEXT:  .LBB1_28: # %wunpsect.exit.thread.loopexit389
-; CHECK-NEXT:  .LBB1_29: # %wunpsect.exit.thread.loopexit391
+; CHECK-NEXT:  .LBB1_25: # %wunpsect.exit.thread.loopexit389
+; CHECK-NEXT:  .LBB1_26: # %wunpsect.exit.thread.loopexit391
 entry:
   %0 = load i32, i32* undef, align 4
   %mul = shl nsw i32 %0, 2
diff --git a/llvm/test/CodeGen/X86/tail-opts.ll b/llvm/test/CodeGen/X86/tail-opts.ll
--- a/llvm/test/CodeGen/X86/tail-opts.ll
+++ b/llvm/test/CodeGen/X86/tail-opts.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -post-RA-scheduler=true | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -post-RA-scheduler=true -disable-cgp-delete-phis | FileCheck %s
 
 declare dso_local void @bar(i32)
 declare dso_local void @car(i32)
diff --git a/llvm/test/CodeGen/X86/x86-shrink-wrapping.ll b/llvm/test/CodeGen/X86/x86-shrink-wrapping.ll
--- a/llvm/test/CodeGen/X86/x86-shrink-wrapping.ll
+++ b/llvm/test/CodeGen/X86/x86-shrink-wrapping.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc %s -o - -enable-shrink-wrap=true -pass-remarks-output=%t | FileCheck %s --check-prefix=ENABLE
+; RUN: llc %s -o - -enable-shrink-wrap=true -pass-remarks-output=%t -disable-cgp-delete-phis | FileCheck %s --check-prefix=ENABLE
 ; RUN: cat %t | FileCheck %s --check-prefix=REMARKS
-; RUN: llc %s -o - -enable-shrink-wrap=false | FileCheck %s --check-prefix=DISABLE
+; RUN: llc %s -o - -enable-shrink-wrap=false -disable-cgp-delete-phis | FileCheck %s --check-prefix=DISABLE
 ;
 ; Note: Lots of tests use inline asm instead of regular calls.
 ; This allows to have a better control on what the allocation will do.
diff --git a/llvm/test/Other/codegenprepare-and-debug.ll b/llvm/test/Other/codegenprepare-and-debug.ll
--- a/llvm/test/Other/codegenprepare-and-debug.ll
+++ b/llvm/test/Other/codegenprepare-and-debug.ll
@@ -61,6 +61,10 @@
 
 lbl:                                              ; preds = %sw.bb, %while.cond.lbl_crit_edge
   %var03.1 = phi i32 [ 0, %while.cond.lbl_crit_edge ], [ 3, %sw.bb ]
+  br label %phi_use
+
+phi_use:
+  store i32 %var03.1, ptr %arg0
   unreachable
 }
 
diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/computedgoto.ll b/llvm/test/Transforms/CodeGenPrepare/X86/computedgoto.ll
--- a/llvm/test/Transforms/CodeGenPrepare/X86/computedgoto.ll
+++ b/llvm/test/Transforms/CodeGenPrepare/X86/computedgoto.ll
@@ -166,14 +166,14 @@
 
 ; Make sure we do the right thing for cases where the indirectbr branches to
 ; the block it terminates.
-define void @loop(ptr nocapture readonly %p) {
+define i64 @loop(ptr nocapture readonly %p) {
 ; CHECK-LABEL: @loop(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[DOTSPLIT:%.*]]
 ; CHECK:       bb0:
 ; CHECK-NEXT:    br label [[DOTSPLIT]]
 ; CHECK:       .split:
-; CHECK-NEXT:    [[MERGE:%.*]] = phi i64 [ [[I_NEXT:%.*]], [[BB0:%.*]] ], [ 0, [[BB0_CLONE:%.*]] ]
+; CHECK-NEXT:    [[MERGE:%.*]] = phi i64 [ [[I_NEXT:%.*]], [[BB0:%.*]] ], [ 0, [[ENTRY:%.*]] ]
 ; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds i64, ptr [[P:%.*]], i64 [[MERGE]]
 ; CHECK-NEXT:    store i64 [[MERGE]], ptr [[TMP0]], align 4
 ; CHECK-NEXT:    [[I_NEXT]] = add nuw nsw i64 [[MERGE]], 1
@@ -182,7 +182,7 @@
 ; CHECK-NEXT:    [[TARGET:%.*]] = load ptr, ptr [[ARRAYIDX]], align 8
 ; CHECK-NEXT:    indirectbr ptr [[TARGET]], [label [[BB0]], label %bb1]
 ; CHECK:       bb1:
-; CHECK-NEXT:    ret void
+; CHECK-NEXT:    ret i64 [[I_NEXT]]
 ;
 entry:
   br label %bb0
@@ -198,7 +198,7 @@
   indirectbr ptr %target, [label %bb0, label %bb1]
 
 bb1:
-  ret void
+  ret i64 %i.next
 }
 
 ; Don't do anything for cases that contain no phis.
@@ -267,7 +267,7 @@
 ; CHECK-NEXT:    br label [[EXIT]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    [[V:%.*]] = phi i32 [ [[R0]], [[BB0]] ], [ [[R1]], [[BB1:%.*]] ]
-; CHECK-NEXT:    ret i32 0
+; CHECK-NEXT:    ret i32 [[V]]
 ;
 {
 entry:
@@ -288,5 +288,5 @@
 
 exit:
   %v = phi i32 [%r0, %bb0], [%r1, %bb1]
-  ret i32 0
+  ret i32 %v
 }
diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/delete-assume-dead-code.ll b/llvm/test/Transforms/CodeGenPrepare/X86/delete-assume-dead-code.ll
--- a/llvm/test/Transforms/CodeGenPrepare/X86/delete-assume-dead-code.ll
+++ b/llvm/test/Transforms/CodeGenPrepare/X86/delete-assume-dead-code.ll
@@ -32,9 +32,7 @@
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT:    [[IV2:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[IV2_INC:%.*]], [[HEADER]] ]
 ; CHECK-NEXT:    [[IV_INC]] = add i32 [[IV]], 1
-; CHECK-NEXT:    [[IV2_INC]] = add i32 [[IV2]], 1
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[IV]], [[N:%.*]]
 ; CHECK-NEXT:    br i1 [[CMP]], label [[EXIT:%.*]], label [[HEADER]]
 ; CHECK:       exit:
@@ -63,9 +61,7 @@
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT:    [[IV2:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[IV2_INC:%.*]], [[HEADER]] ]
 ; CHECK-NEXT:    [[IV_INC]] = add i32 [[IV]], 1
-; CHECK-NEXT:    [[IV2_INC]] = add i32 [[IV2]], 1
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[IV]], [[N:%.*]]
 ; CHECK-NEXT:    br i1 [[CMP]], label [[EXIT:%.*]], label [[HEADER]]
 ; CHECK:       exit:
@@ -95,9 +91,7 @@
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT:    [[IV2:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[IV2_INC:%.*]], [[HEADER]] ]
 ; CHECK-NEXT:    [[IV_INC]] = add i32 [[IV]], 1
-; CHECK-NEXT:    [[IV2_INC]] = add i32 [[IV2]], 1
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[IV]], [[N:%.*]]
 ; CHECK-NEXT:    br i1 [[CMP]], label [[EXIT:%.*]], label [[HEADER]]
 ; CHECK:       exit:
diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-base.ll b/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-base.ll
--- a/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-base.ll
+++ b/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-base.ll
@@ -1,5 +1,5 @@
-; RUN: opt -S -codegenprepare -disable-complex-addr-modes=false -addr-sink-new-phis=true -addr-sink-new-select=true  %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-YES
-; RUN: opt -S -codegenprepare -disable-complex-addr-modes=false -addr-sink-new-phis=false -addr-sink-new-select=true %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NO
+; RUN: opt -S -codegenprepare -disable-complex-addr-modes=false -addr-sink-new-phis=true -addr-sink-new-select=true -disable-cgp-delete-phis  %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-YES
+; RUN: opt -S -codegenprepare -disable-complex-addr-modes=false -addr-sink-new-phis=false -addr-sink-new-select=true -disable-cgp-delete-phis %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NO
 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"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll b/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll
--- a/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll
+++ b/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -codegenprepare -disable-complex-addr-modes=false  %s | FileCheck %s --check-prefix=CHECK
+; RUN: opt -S -codegenprepare -disable-complex-addr-modes=false -disable-cgp-delete-phis %s | FileCheck %s --check-prefix=CHECK
 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"
 target triple = "x86_64-unknown-linux-gnu"