Index: lib/Tooling/ASTDiff/ASTDiff.cpp
===================================================================
--- lib/Tooling/ASTDiff/ASTDiff.cpp
+++ lib/Tooling/ASTDiff/ASTDiff.cpp
@@ -68,7 +68,8 @@
   // Compute ChangeKind for each node based on similarity.
   void computeChangeKinds(Mapping &M);
 
-  NodeId getMapped(const std::unique_ptr<SyntaxTree::Impl> &Tree, NodeId Id) const {
+  NodeId getMapped(const std::unique_ptr<SyntaxTree::Impl> &Tree,
+                   NodeId Id) const {
     if (&*Tree == &T1)
       return TheMapping.getDst(Id);
     assert(&*Tree == &T2 && "Invalid tree.");
@@ -157,12 +158,23 @@
   void setLeftMostDescendants();
 };
 
+static bool isSpecializedNodeExcluded(const Decl *D) { return D->isImplicit(); }
+static bool isSpecializedNodeExcluded(const Stmt *S) { return false; }
+
 template <class T>
 static bool isNodeExcluded(const SourceManager &SrcMgr, T *N) {
   if (!N)
     return true;
   SourceLocation SLoc = N->getLocStart();
-  return SLoc.isValid() && SrcMgr.isInSystemHeader(SLoc);
+  if (SLoc.isValid()) {
+    // Ignore everything from other files.
+    if (!SrcMgr.isInMainFile(SLoc))
+      return true;
+    // Ignore macros.
+    if (SLoc != SrcMgr.getSpellingLoc(SLoc))
+      return true;
+  }
+  return isSpecializedNodeExcluded(N);
 }
 
 namespace {
@@ -179,6 +191,8 @@
     return true;
   }
   bool TraverseStmt(Stmt *S) {
+    if (S)
+      S = S->IgnoreImplicit();
     if (isNodeExcluded(Tree.AST.getSourceManager(), S))
       return true;
     ++Count;
@@ -241,6 +255,8 @@
     return true;
   }
   bool TraverseStmt(Stmt *S) {
+    if (S)
+      S = S->IgnoreImplicit();
     if (isNodeExcluded(Tree.AST.getSourceManager(), S))
       return true;
     auto SavedState = PreTraverse(S);
@@ -900,7 +916,8 @@
   return TreeImpl->findPositionInParent(Id);
 }
 
-std::pair<unsigned, unsigned> SyntaxTree::getSourceRangeOffsets(const Node &N) const {
+std::pair<unsigned, unsigned>
+SyntaxTree::getSourceRangeOffsets(const Node &N) const {
   const SourceManager &SrcMgr = TreeImpl->AST.getSourceManager();
   SourceRange Range = N.ASTNode.getSourceRange();
   SourceLocation BeginLoc = Range.getBegin();
Index: test/Tooling/clang-diff-ast.cpp
===================================================================
--- test/Tooling/clang-diff-ast.cpp
+++ test/Tooling/clang-diff-ast.cpp
@@ -12,7 +12,8 @@
   // CHECK: IntegerLiteral: 1
   auto i = 1;
   // CHECK: CallExpr(
-  // CHECK: DeclRefExpr: f(
+  // CHECK-NOT: ImplicitCastExpr
+  // CHECK-NEXT: DeclRefExpr: f(
   f();
   // CHECK: BinaryOperator: =(
   i = i;
@@ -37,6 +38,7 @@
     if (i == 0)
       // CHECK: StringLiteral: foo(
       return "foo";
+    // CHECK-NOT: ImplicitCastExpr
     return 0;
   }
 
@@ -48,3 +50,23 @@
     int x = m;
   }
 };
+
+#define M (void)1
+#define MA(a, b) (void)a, b
+// CHECK: FunctionDecl
+// CHECK-NEXT: CompoundStmt
+void macros() {
+  M;
+  MA(1, 2);
+}
+// CHECK-NEXT: NamespaceDecl
+
+#ifndef GUARD
+#define GUARD
+namespace world {
+// nodes from other files are excluded, there should be no output from this
+// point on
+// CHECK-NOT: {{.}}
+#include "clang-diff-ast.cpp"
+}
+#endif
Index: test/Tooling/clang-diff-json.cpp
===================================================================
--- test/Tooling/clang-diff-json.cpp
+++ test/Tooling/clang-diff-json.cpp
@@ -3,9 +3,9 @@
 // RUN: | FileCheck %s
 
 // CHECK: "begin": 299,
-// CHECK: "type": "CXXRecordDecl",
 // CHECK: "type": "FieldDecl",
 // CHECK: "end": 319,
+// CHECK: "type": "CXXRecordDecl",
 class A {
   int x;
 };