diff --git a/mlir/lib/Transforms/StripDebugInfo.cpp b/mlir/lib/Transforms/StripDebugInfo.cpp
--- a/mlir/lib/Transforms/StripDebugInfo.cpp
+++ b/mlir/lib/Transforms/StripDebugInfo.cpp
@@ -21,9 +21,20 @@
 } // end anonymous namespace
 
 void StripDebugInfo::runOnOperation() {
-  // Strip the debug info from all operations.
   auto unknownLoc = UnknownLoc::get(&getContext());
-  getOperation()->walk([&](Operation *op) { op->setLoc(unknownLoc); });
+
+  // Strip the debug info from all operations.
+  getOperation()->walk([&](Operation *op) {
+    op->setLoc(unknownLoc);
+    // Strip block arguments debug info.
+    for (Region &region : op->getRegions()) {
+      for (Block &block : region.getBlocks()) {
+        for (BlockArgument &arg : block.getArguments()) {
+          arg.setLoc(unknownLoc);
+        }
+      }
+    }
+  });
 }
 
 /// Creates a pass to strip debug information from a function.
diff --git a/mlir/test/Transforms/strip-debuginfo.mlir b/mlir/test/Transforms/strip-debuginfo.mlir
--- a/mlir/test/Transforms/strip-debuginfo.mlir
+++ b/mlir/test/Transforms/strip-debuginfo.mlir
@@ -17,6 +17,13 @@
   affine.if #set0(%2) {
   } loc(fused<"myPass">["foo", "foo2"])
 
+  "foo.region"() ({
+  // CHECK: ^bb0(%{{.*}}: i32 loc(unknown), %{{.*}}: i32 loc(unknown)):
+ ^bb0(%a0: i32 loc("argloc"), %z: i32 loc("argloc2")):
+    %s = addi %a0, %a0 : i32
+    "foo.yield"(%s) : (i32) -> ()
+  }) : () -> ()
+
   // CHECK: return %0 : i32 loc(unknown)
   return %1 : i32 loc("bar")
 }