Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -13037,7 +13037,7 @@
 
     if (!FD->isInvalidDecl()) {
       // Don't diagnose unused parameters of defaulted or deleted functions.
-      if (!FD->isDeleted() && !FD->isDefaulted())
+      if (!FD->isDeleted() && !FD->isDefaulted() && !FD->hasSkippedBody())
         DiagnoseUnusedParameters(FD->parameters());
       DiagnoseSizeOfParametersAndReturnValue(FD->parameters(),
                                              FD->getReturnType(), FD);
@@ -13132,7 +13132,8 @@
     assert(MD == getCurMethodDecl() && "Method parsing confused");
     MD->setBody(Body);
     if (!MD->isInvalidDecl()) {
-      DiagnoseUnusedParameters(MD->parameters());
+      if (!MD->hasSkippedBody())
+        DiagnoseUnusedParameters(MD->parameters());
       DiagnoseSizeOfParametersAndReturnValue(MD->parameters(),
                                              MD->getReturnType(), MD);
 
Index: test/Index/skipped-bodies-unused.cpp
===================================================================
--- test/Index/skipped-bodies-unused.cpp
+++ test/Index/skipped-bodies-unused.cpp
@@ -0,0 +1,8 @@
+// RUN: env CINDEXTEST_SKIP_FUNCTION_BODIES=1 c-index-test -test-load-source all %s -Wunused-parameter 2>&1 \
+// RUN: | FileCheck %s
+
+// No 'unused parameter' warnings should be shown when skipping the function bodies.
+inline int foo(int used, int unused) {
+    used = 100;
+}
+// CHECK-NOT: warning: unused parameter