diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -4295,9 +4295,9 @@
     bool PrintAllTypes = false;
     Type *TheType = Operand->getType();
 
-    // Select, Store and ShuffleVector always print all types.
-    if (isa<SelectInst>(I) || isa<StoreInst>(I) || isa<ShuffleVectorInst>(I)
-        || isa<ReturnInst>(I)) {
+    // Select, Store, ShuffleVector and CmpXchg always print all types.
+    if (isa<SelectInst>(I) || isa<StoreInst>(I) || isa<ShuffleVectorInst>(I) ||
+        isa<ReturnInst>(I) || isa<AtomicCmpXchgInst>(I)) {
       PrintAllTypes = true;
     } else {
       for (unsigned i = 1, E = I.getNumOperands(); i != E; ++i) {
diff --git a/llvm/test/Assembler/opaque-ptr.ll b/llvm/test/Assembler/opaque-ptr.ll
--- a/llvm/test/Assembler/opaque-ptr.ll
+++ b/llvm/test/Assembler/opaque-ptr.ll
@@ -107,6 +107,14 @@
     ret void
 }
 
+; CHECK: define void @cmpxchg_ptr(ptr %p, ptr %a, ptr %b)
+; CHECK:     %val_success = cmpxchg ptr %p, ptr %a, ptr %b acq_rel monotonic
+; CHECK:     ret void
+define void @cmpxchg_ptr(ptr %p, ptr %a, ptr %b) {
+    %val_success = cmpxchg ptr %p, ptr %a, ptr %b acq_rel monotonic
+    ret void
+}
+
 ; CHECK: define void @atomicrmw(ptr %a, i32 %i)
 ; CHECK:     %b = atomicrmw add ptr %a, i32 %i acquire
 ; CHECK:     ret void