diff --git a/include/llvm/ADT/SmallPtrSet.h b/include/llvm/ADT/SmallPtrSet.h
index c7f5e5bfc0f..b52aebf7d55 100644
--- a/include/llvm/ADT/SmallPtrSet.h
+++ b/include/llvm/ADT/SmallPtrSet.h
@@ -293,14 +293,16 @@ public:
 
   SmallPtrSet<PtrType, SmallSize> &
   operator=(const SmallPtrSet<PtrType, SmallSize> &RHS) {
-    CopyFrom(RHS);
+    if (&RHS != this)
+      CopyFrom(RHS);
     return *this;
   }
 
 #if LLVM_HAS_RVALUE_REFERENCES
   SmallPtrSet<PtrType, SmallSize>&
   operator=(SmallPtrSet<PtrType, SmallSize> &&RHS) {
-    MoveFrom(SmallSizePowTwo, std::move(RHS));
+    if (&RHS != this)
+      MoveFrom(SmallSizePowTwo, std::move(RHS));
     return *this;
   }
 #endif
diff --git a/lib/Support/SmallPtrSet.cpp b/lib/Support/SmallPtrSet.cpp
index fa8d91545e7..f873d91d6e0 100644
--- a/lib/Support/SmallPtrSet.cpp
+++ b/lib/Support/SmallPtrSet.cpp
@@ -218,8 +218,7 @@ SmallPtrSetImpl::SmallPtrSetImpl(const void **SmallStorage, unsigned SmallSize,
 /// CopyFrom - implement operator= from a smallptrset that has the same pointer
 /// type, but may have a different small size.
 void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) {
-  if (&RHS == this)
-    return;
+  assert(&RHS != this && "Self-copy should be handled by the caller.");
 
   if (isSmall() && RHS.isSmall())
     assert(CurArraySize == RHS.CurArraySize &&
@@ -256,6 +255,8 @@ void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) {
 
 #if LLVM_HAS_RVALUE_REFERENCES
 void SmallPtrSetImpl::MoveFrom(unsigned SmallSize, SmallPtrSetImpl &&RHS) {
+  assert(&RHS != this && "Self-move should be handled by the caller.");
+
   if (!isSmall())
     free(CurArray);