Index: clang/lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- clang/lib/CodeGen/CGDebugInfo.cpp
+++ clang/lib/CodeGen/CGDebugInfo.cpp
@@ -4292,7 +4292,9 @@
   auto *Scope = cast<llvm::DIScope>(LexicalBlockStack.back());
   StringRef Name = VD->getName();
   if (!Name.empty()) {
-    if (VD->hasAttr<BlocksAttr>()) {
+    // __block vars are stored on the heap if they are captured by a block that
+    // can escape the local scope.
+    if (VD->isEscapingByref()) {
       // Here, we need an offset *into* the alloca.
       CharUnits offset = CharUnits::fromQuantity(32);
       Expr.push_back(llvm::dwarf::DW_OP_plus_uconst);
Index: clang/test/CodeGen/debug-info-block-expr-escape-func.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/debug-info-block-expr-escape-func.c
@@ -0,0 +1,21 @@
+// Verify that the desired DIExpression are generated for escaping (i.e, not
+// 'noescape') blocks.
+
+// RUN: %clang_cc1 -fblocks -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -DDEAD_CODE -fblocks -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s
+
+typedef void (^BlockTy)();
+void escapeFunc(BlockTy);
+
+void test() {
+// CHECK-LABEL: void @test
+// CHECK: call void @llvm.dbg.declare({{.*}}!DIExpression(DW_OP_plus_uconst, {{[0-9]+}}, DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}){{.*}})
+// Prevent accidential passes due to DIExpressions() in the block init code.
+// CHECK-LABEL: %byref.isa =
+  __block int i;
+// Blocks in dead code branches still capture __block variables.
+#ifdef DEAD_CODE
+  if (0)
+#endif
+  escapeFunc(^{ (void)i; });
+}
Index: clang/test/CodeGen/debug-info-block-expr-noescape-func.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/debug-info-block-expr-noescape-func.c
@@ -0,0 +1,15 @@
+// Verify that the desired DIExpression are generated for noescape blocks.
+
+// RUN: %clang_cc1 -fblocks -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s
+
+typedef void (^BlockTy)();
+void noEscapeFunc(__attribute__((noescape)) BlockTy);
+
+void test() {
+// CHECK-LABEL: void @test
+// CHECK: call void @llvm.dbg.declare({{.*}}!DIExpression())
+// Prevent accidential passes due to DIExpressions() in the block init code.
+// CHECK-LABEL: %block.isa =
+  __block int i;
+  noEscapeFunc(^{ (void)i; });
+}
Index: clang/test/CodeGen/debug-info-block-expr-unused.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/debug-info-block-expr-unused.c
@@ -0,0 +1,18 @@
+// Verify that the desired DIExpression are generated for __block vars not used
+// in any block.
+
+// RUN: %clang_cc1 -fblocks -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s
+
+typedef void (^BlockTy)();
+void noEscapeFunc(__attribute__((noescape)) BlockTy);
+
+int test() {
+// CHECK-LABEL: i32 @test
+// CHECK: call void @llvm.dbg.declare({{.*}}!DIExpression())
+  __block int i;
+// Use i (not inside a block).
+  ++i;
+// Prevent accidential passes due to DIExpressions() in the block init code.
+// CHECK-LABEL: ret i32 1234
+  return 1234;
+}