Index: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -4350,6 +4350,13 @@
   bool MadeIRChange = false;
   if (ShouldLowerDbgDeclare)
     MadeIRChange = LowerDbgDeclare(F);
+  // LowerDbgDeclare calls RemoveRedundantDbgInstrs, but LowerDbgDeclare will
+  // almost never return true when running an assignment tracking build. Take
+  // this opportunity to do some clean up for assignment tracking builds too.
+  if (!MadeIRChange && getEnableAssignmentTracking()) {
+    for (auto &BB : F)
+      RemoveRedundantDbgInstrs(&BB);
+  }
 
   // Iterate while there is work to do.
   unsigned Iteration = 0;