Index: test/Tooling/clang-diff-args.sh
===================================================================
--- test/Tooling/clang-diff-args.sh
+++ test/Tooling/clang-diff-args.sh
@@ -6,3 +6,7 @@
 RUN: clang-diff -ast-dump -extra-arg=-Da=X        %t.cpp -- 2>&1 | FileCheck %t1
 RUN: clang-diff -ast-dump -extra-arg-before=-Da=X %t.cpp -- 2>&1 | FileCheck %t1
 RUN: clang-diff -ast-dump %t.cpp -- 2>&1 -Da=X | FileCheck %t1
+
+RUN: echo "// CHECK-NOT: {{.}}" > %t-no-output
+RUN: clang-diff %S/clang-diff-ast.cpp %S/clang-diff-ast.cpp -- 2>&1 -std=c++11 \
+RUN: | FileCheck -allow-empty %t-no-output
Index: test/Tooling/clang-diff-basic.cpp
===================================================================
--- test/Tooling/clang-diff-basic.cpp
+++ test/Tooling/clang-diff-basic.cpp
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -E %s > %T/src.cpp
 // RUN: %clang_cc1 -E %s > %T/dst.cpp -DDEST
-// RUN: clang-diff %T/src.cpp %T/dst.cpp -- | FileCheck %s
+// RUN: clang-diff -dump-matches %T/src.cpp %T/dst.cpp -- | FileCheck %s
 
 #ifndef DEST
 namespace src {
Index: tools/clang-diff/ClangDiff.cpp
===================================================================
--- tools/clang-diff/ClangDiff.cpp
+++ tools/clang-diff/ClangDiff.cpp
@@ -33,6 +33,10 @@
     cl::desc("Print the internal representation of the AST as JSON."),
     cl::init(false), cl::cat(ClangDiffCategory));
 
+static cl::opt<bool>
+    PrintMatches("dump-matches", cl::desc("Print the matched nodes."),
+                 cl::init(false), cl::cat(ClangDiffCategory));
+
 static cl::opt<std::string> SourcePath(cl::Positional, cl::desc("<source>"),
                                        cl::Required,
                                        cl::cat(ClangDiffCategory));
@@ -280,7 +284,7 @@
 
   for (diff::NodeId Dst : DstTree) {
     diff::NodeId Src = Diff.getMapped(DstTree, Dst);
-    if (Src.isValid()) {
+    if (PrintMatches && Src.isValid()) {
       llvm::outs() << "Match ";
       printNode(llvm::outs(), SrcTree, Src);
       llvm::outs() << " to ";