diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -123,8 +123,13 @@
 DEBUG_COUNTER(VisitCounter, "instcombine-visit",
               "Controls which instructions are visited");
 
+// FIXME: these limits eventually should be as low as 2.
 static constexpr unsigned InstCombineDefaultMaxIterations = 1000;
+#ifndef NDEBUG
+static constexpr unsigned InstCombineDefaultInfiniteLoopThreshold = 100;
+#else
 static constexpr unsigned InstCombineDefaultInfiniteLoopThreshold = 1000;
+#endif
 
 static cl::opt<bool>
 EnableCodeSinking("instcombine-code-sinking", cl::desc("Enable code sinking"),