diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -17159,6 +17159,9 @@
   if (getCurFunction())
     getCurFunction()->addBlock(BD);
 
+  if (BD->isInvalidDecl())
+    return CreateRecoveryExpr(Result->getBeginLoc(), Result->getEndLoc(),
+        {Result}, Result->getType());
   return Result;
 }
 
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -3730,6 +3730,13 @@
   if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
     FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
 
+  BlockScopeInfo *CurBlock = dyn_cast<BlockScopeInfo>(CurCap);
+  if (CurBlock && CurCap->HasImplicitReturnType) {
+    BlockDecl *BD = CurBlock->TheDecl;
+    if (!BD->isInvalidDecl() && RetValExp && RetValExp->containsErrors())
+      BD->setInvalidDecl();
+  }
+
   return Result;
 }
 
diff --git a/clang/test/SemaObjC/crash-on-val-dep-block-expr.m b/clang/test/SemaObjC/crash-on-val-dep-block-expr.m
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaObjC/crash-on-val-dep-block-expr.m
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fblocks -fsyntax-only -verify %s
+// no crash
+
+int (^a)() = ^() {
+  return c; // expected-error {{use of undeclared identifier 'c'}}
+};
+
+int (^b)() = (^() {
+  return c; // expected-error {{use of undeclared identifier 'c'}}
+});