diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index 61b8818..da10687 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -119,6 +119,7 @@
         "liblog",
         "libcutils",
         "libutils",
+        "libbinderthreadstate",
     ],
 
     header_libs: [
diff --git a/libs/binder/IPCThreadState.cpp b/libs/binder/IPCThreadState.cpp
index b2217b5..f052bcb 100644
--- a/libs/binder/IPCThreadState.cpp
+++ b/libs/binder/IPCThreadState.cpp
@@ -17,6 +17,7 @@
 #define LOG_TAG "IPCThreadState"
 
 #include <binder/IPCThreadState.h>
+#include <binderthreadstate/IPCThreadStateBase.h>
 
 #include <binder/Binder.h>
 #include <binder/BpBinder.h>
@@ -742,6 +743,7 @@
     clearCaller();
     mIn.setDataCapacity(256);
     mOut.setDataCapacity(256);
+    mIPCThreadStateBase = IPCThreadStateBase::self();
 }
 
 IPCThreadState::~IPCThreadState()
@@ -1082,6 +1084,9 @@
                 "Not enough command data for brTRANSACTION");
             if (result != NO_ERROR) break;
 
+            //Record the fact that we're in a binder call.
+            mIPCThreadStateBase->pushCurrentState(
+                IPCThreadStateBase::CallState::BINDER);
             Parcel buffer;
             buffer.ipcSetDataReference(
                 reinterpret_cast<const uint8_t*>(tr.data.ptr.buffer),
@@ -1129,6 +1134,7 @@
                 error = the_context_object->transact(tr.code, buffer, &reply, tr.flags);
             }
 
+            mIPCThreadStateBase->popCurrentState();
             //ALOGI("<<<< TRANSACT from pid %d restore pid %d uid %d\n",
             //     mCallingPid, origPid, origUid);
 
@@ -1192,6 +1198,10 @@
     return result;
 }
 
+bool IPCThreadState::isServingCall() const {
+    return mIPCThreadStateBase->getCurrentBinderCallState() == IPCThreadStateBase::CallState::BINDER;
+}
+
 void IPCThreadState::threadDestructor(void *st)
 {
         IPCThreadState* const self = static_cast<IPCThreadState*>(st);
diff --git a/libs/binder/include/binder/IPCThreadState.h b/libs/binder/include/binder/IPCThreadState.h
index dce3f38..40b51ad 100644
--- a/libs/binder/include/binder/IPCThreadState.h
+++ b/libs/binder/include/binder/IPCThreadState.h
@@ -29,6 +29,8 @@
 // ---------------------------------------------------------------------------
 namespace android {
 
+class IPCThreadStateBase;
+
 class IPCThreadState
 {
 public:
@@ -89,6 +91,33 @@
             // the maximum number of binder threads threads allowed for this process.
             void                blockUntilThreadAvailable();
 
+
+            // Is this thread currently serving a binder call. This method
+            // returns true if while traversing backwards from the function call
+            // stack for this thread, we encounter a function serving a binder
+            // call before encountering a hwbinder call / hitting the end of the
+            // call stack.
+            // Eg: If thread T1 went through the following call pattern
+            //     1) T1 receives and executes hwbinder call H1.
+            //     2) While handling H1, T1 makes binder call B1.
+            //     3) The handler of B1, calls into T1 with a callback B2.
+            // If isServingCall() is called during H1 before 3), this method
+            // will return false, else true.
+            //
+            //  ----
+            // | B2 | ---> While callback B2 is being handled, during 3).
+            //  ----
+            // | H1 | ---> While H1 is being handled.
+            //  ----
+            // Fig: Thread Call stack while handling B2
+            //
+            // This is since after 3), while traversing the thread call stack,
+            // we hit a binder call before a hwbinder call / end of stack. This
+            // method may be typically used to determine whether to use
+            // hardware::IPCThreadState methods or IPCThreadState methods to
+            // infer information about thread state.
+            bool                isServingCall() const;
+
 private:
                                 IPCThreadState();
                                 ~IPCThreadState();
@@ -128,6 +157,7 @@
             uid_t               mCallingUid;
             int32_t             mStrictModePolicy;
             int32_t             mLastTransactionBinderFlags;
+            IPCThreadStateBase  *mIPCThreadStateBase;
 };
 
 }; // namespace android