diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 1f97f0c1ac9975..6a406314f63c00 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3355,6 +3355,12 @@ static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
   I->moveBefore(&*InsertPos);
   ++NumSunkInst;
 
+  // Drop the debug loc of non-inlinable instructions. This prevents
+  // single-stepping from going backwards. See HowToUpdateDebugInfo.rst for
+  // the full rationale.
+  if (!isa<CallBase>(I))
+    I->setDebugLoc(DebugLoc());
+
   // Also sink all related debug uses from the source basic block. Otherwise we
   // get debug use before the def. Attempt to salvage debug uses first, to
   // maximise the range variables have location for. If we cannot salvage, then
diff --git a/llvm/test/Transforms/InstCombine/sink_to_unreachable_dbg.ll b/llvm/test/Transforms/InstCombine/sink_to_unreachable_dbg.ll
new file mode 100644
index 00000000000000..e642276224b84c
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/sink_to_unreachable_dbg.ll
@@ -0,0 +1,46 @@
+; RUN: opt -debugify -debugify-level=locations -instcombine -S < %s | FileCheck %s
+
+; CHECK-LABEL: @test1(
+; CHECK: [[phi:%.*]] = phi i32
+; CHECK-NEXT: [[add:%.*]] = add i32 {{.*}}, 1{{$}}
+; CHECK-NEXT: add i32 [[phi]], [[add]], !dbg
+define i32 @test1(i32 %0, i1 %1) {
+  %3 = add i32 %0, 1
+  br i1 %1, label %4, label %5
+
+4:                                                ; preds = %2
+  br label %6
+
+5:                                                ; preds = %2
+  br label %6
+
+6:                                                ; preds = %5, %4
+  %7 = phi i32 [ 0, %4 ], [ 1, %5 ]
+  %8 = add i32 %7, %3
+  ret i32 %8
+}
+
+; Function Attrs: nounwind readnone
+declare i32 @external(i32) #0
+
+; CHECK-LABEL: @test2(
+; CHECK: [[phi:%.*]] = phi i32
+; CHECK-NEXT: [[add:%.*]] = call i32 @external(i32 {{.*}}), !dbg
+; CHECK-NEXT: add i32 [[phi]], [[add]], !dbg
+define i32 @test2(i32 %0, i1 %1) {
+  %3 = call i32 @external(i32 %0)
+  br i1 %1, label %4, label %5
+
+4:                                                ; preds = %2
+  br label %6
+
+5:                                                ; preds = %2
+  br label %6
+
+6:                                                ; preds = %5, %4
+  %7 = phi i32 [ 0, %4 ], [ 1, %5 ]
+  %8 = add i32 %7, %3
+  ret i32 %8
+}
+
+attributes #0 = { nounwind readnone }