diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
--- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -84,9 +84,16 @@
              "for faster compile. Caps the MemorySSA clobbering calls."));
 
 static cl::opt<bool> EarlyCSEDebugHash(
-    "earlycse-debug-hash", cl::init(false), cl::Hidden,
-    cl::desc("Perform extra assertion checking to verify that SimpleValue's hash "
-             "function is well-behaved w.r.t. its isEqual predicate"));
+    "earlycse-debug-hash",
+#ifdef EXPENSIVE_CHECKS
+    cl::init(true),
+#else
+    cl::init(false),
+#endif
+    cl::Hidden,
+    cl::desc(
+        "Perform extra assertion checking to verify that SimpleValue's hash "
+        "function is well-behaved w.r.t. its isEqual predicate"));
 
 //===----------------------------------------------------------------------===//
 // SimpleValue