diff --git a/src/init.cpp b/src/init.cpp
index 1d2d3a9721..70985a489f 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1153,8 +1153,16 @@ bool AppInitParameterInteraction()
         // Minimal effort at forwards compatibility
         std::string strReplacementModeList = gArgs.GetArg("-mempoolreplacement", "");  // default is impossible
         std::vector<std::string> vstrReplacementModes;
-        boost::split(vstrReplacementModes, strReplacementModeList, boost::is_any_of(","));
+        boost::split(vstrReplacementModes, strReplacementModeList, boost::is_any_of(",+"));
         fEnableReplacement = (std::find(vstrReplacementModes.begin(), vstrReplacementModes.end(), "fee") != vstrReplacementModes.end());
+        if (fEnableReplacement) {
+            fReplacementHonourOptOut = (std::find(vstrReplacementModes.begin(), vstrReplacementModes.end(), "-optin") == vstrReplacementModes.end());
+            if (!fReplacementHonourOptOut) {
+                nLocalServices = ServiceFlags(nLocalServices | NODE_REPLACE_BY_FEE);
+            }
+        } else {
+            fReplacementHonourOptOut = true;
+        }
     }
 
     return true;
diff --git a/src/validation.cpp b/src/validation.cpp
index d7bd48d4ab..918588ebbb 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -233,6 +233,7 @@ size_t nCoinCacheUsage = 5000 * 300;
 uint64_t nPruneTarget = 0;
 int64_t nMaxTipAge = DEFAULT_MAX_TIP_AGE;
 bool fEnableReplacement = DEFAULT_ENABLE_REPLACEMENT;
+bool fReplacementHonourOptOut = DEFAULT_REPLACEMENT_HONOUR_OPTOUT;
 
 uint256 hashAssumeValid;
 arith_uint256 nMinimumChainWork;
@@ -623,6 +624,7 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                 bool fReplacementOptOut = true;
                 if (fEnableReplacement)
                 {
+                  if (fReplacementHonourOptOut) {
                     for (const CTxIn &_txin : ptxConflicting->vin)
                     {
                         if (_txin.nSequence <= MAX_BIP125_RBF_SEQUENCE)
@@ -631,6 +633,9 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
                             break;
                         }
                     }
+                  } else {
+                        fReplacementOptOut = false;
+                  }
                 }
                 if (fReplacementOptOut) {
                     return state.Invalid(false, REJECT_DUPLICATE, "txn-mempool-conflict");
diff --git a/src/validation.h b/src/validation.h
index 4965ff152a..25f9692fa0 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -122,6 +122,7 @@ static const unsigned int DEFAULT_BANSCORE_THRESHOLD = 100;
 static const bool DEFAULT_PERSIST_MEMPOOL = true;
 /** Default for -mempoolreplacement */
 static const bool DEFAULT_ENABLE_REPLACEMENT = true;
+static const bool DEFAULT_REPLACEMENT_HONOUR_OPTOUT = true;
 /** Default for using fee filter */
 static const bool DEFAULT_FEEFILTER = true;
 
@@ -169,6 +170,7 @@ extern CAmount maxTxFee;
 /** If the tip is older than this (in seconds), the node is considered to be in initial block download. */
 extern int64_t nMaxTipAge;
 extern bool fEnableReplacement;
+extern bool fReplacementHonourOptOut;
 
 /** Block hash whose ancestors we will assume to have valid scripts without checking them. */
 extern uint256 hashAssumeValid;