diff --git a/core/jni/AndroidRuntime.cpp b/core/jni/AndroidRuntime.cpp
index 07505a5..2dfebe5 100644
--- a/core/jni/AndroidRuntime.cpp
+++ b/core/jni/AndroidRuntime.cpp
@@ -20,6 +20,7 @@
 
 #include <android_runtime/AndroidRuntime.h>
 #include <binder/IBinder.h>
+#include <binder/IPCThreadState.h>
 #include <binder/IServiceManager.h>
 #include <utils/Log.h>
 #include <utils/misc.h>
@@ -431,6 +432,20 @@
     LOG_PRI_VA(ANDROID_LOG_INFO, "vm-printf", format, ap);
 }
 
+/**
+ * The VM calls this when mutex contention debugging is enabled to
+ * determine whether or not the blocked thread was a "sensitive thread"
+ * for user responsiveness/smoothess.
+ *
+ * Our policy for this is whether or not we're tracing any StrictMode
+ * events on this thread (which we might've inherited via Binder calls
+ * into us)
+ */
+static bool runtime_isSensitiveThread() {
+    IPCThreadState* state = IPCThreadState::selfOrNull();
+    return state && state->getStrictModePolicy() != 0;
+}
+
 
 /**
  * Add VM arguments to the to-be-executed VM
@@ -618,6 +633,11 @@
     opt.optionString = "vfprintf";
     mOptions.add(opt);
 
+    /* register the framework-specific "is sensitive thread" hook */
+    opt.extraInfo = (void*) runtime_isSensitiveThread;
+    opt.optionString = "sensitiveThread";
+    mOptions.add(opt);
+
     opt.extraInfo = NULL;
 
     /* enable verbose; standard options are { jni, gc, class } */
diff --git a/include/binder/IPCThreadState.h b/include/binder/IPCThreadState.h
index b54718f..3378d97 100644
--- a/include/binder/IPCThreadState.h
+++ b/include/binder/IPCThreadState.h
@@ -33,6 +33,7 @@
 {
 public:
     static  IPCThreadState*     self();
+    static  IPCThreadState*     selfOrNull();  // self(), but won't instantiate
     
             sp<ProcessState>    process();
             
diff --git a/libs/binder/IPCThreadState.cpp b/libs/binder/IPCThreadState.cpp
index 13c58f0..95cfddf 100644
--- a/libs/binder/IPCThreadState.cpp
+++ b/libs/binder/IPCThreadState.cpp
@@ -318,6 +318,16 @@
     goto restart;
 }
 
+IPCThreadState* IPCThreadState::selfOrNull()
+{
+    if (gHaveTLS) {
+        const pthread_key_t k = gTLS;
+        IPCThreadState* st = (IPCThreadState*)pthread_getspecific(k);
+        return st;
+    }
+    return NULL;
+}
+
 void IPCThreadState::shutdown()
 {
     gShutdown = true;