diff -r d96c9271bb59 -r 0a83a8d08c9e src/mem/ruby/slicc_interface/AbstractController.cc
--- a/src/mem/ruby/slicc_interface/AbstractController.cc	Fri Oct 16 08:09:18 2015 -0500
+++ b/src/mem/ruby/slicc_interface/AbstractController.cc	Fri Oct 16 08:37:57 2015 -0500
@@ -191,6 +191,12 @@
     m_block_map[addr] = port;
 }
 
+bool
+AbstractController::isBlocked(Addr addr) const
+{
+    return m_is_blocking && (m_block_map.find(addr) != m_block_map.end());
+}
+
 void
 AbstractController::unblock(Addr addr)
 {
diff -r d96c9271bb59 -r 0a83a8d08c9e src/mem/ruby/system/Sequencer.cc
--- a/src/mem/ruby/system/Sequencer.cc	Fri Oct 16 08:09:18 2015 -0500
+++ b/src/mem/ruby/system/Sequencer.cc	Fri Oct 16 08:37:57 2015 -0500
@@ -172,6 +172,13 @@
     }
 
     Addr line_addr = makeLineAddress(pkt->getAddr());
+
+    // Check if the line is blocked for a Locked_RMW
+    if (m_controller->isBlocked(line_addr) &&
+        (request_type != RubyRequestType_Locked_RMW_Write)) {
+        return RequestStatus_Aliased;
+    }
+
     // Create a default entry, mapping the address to NULL, the cast is
     // there to make gcc 4.4 happy
     RequestTable::value_type default_entry(line_addr,
@@ -381,6 +388,9 @@
     if(!m_usingNetworkTester)
         success = handleLlsc(address, request);
 
+    // Handle SLICC block_on behavior for Locked_RMW accesses. NOTE: the
+    // address variable here is assumed to be a line address, so when
+    // blocking buffers, must check line addresses.
     if (request->m_type == RubyRequestType_Locked_RMW_Read) {
         m_controller->blockOnQueue(address, m_mandatory_q_ptr);
     } else if (request->m_type == RubyRequestType_Locked_RMW_Write) {
diff -r d96c9271bb59 -r 0a83a8d08c9e src/mem/ruby/slicc_interface/AbstractController.hh
--- a/src/mem/ruby/slicc_interface/AbstractController.hh	Fri Oct 16 08:09:18 2015 -0500
+++ b/src/mem/ruby/slicc_interface/AbstractController.hh	Fri Oct 16 08:37:57 2015 -0500
@@ -72,6 +72,7 @@
 
     // return instance name
     void blockOnQueue(Addr, MessageBuffer*);
+    bool isBlocked(Addr) const;
     void unblock(Addr);
 
     virtual MessageBuffer* getMandatoryQueue() const = 0;