diff --git a/sp/src/game/server/ai_basenpc.cpp b/sp/src/game/server/ai_basenpc.cpp
index b690f9a06d5..6cff9950fbf 100644
--- a/sp/src/game/server/ai_basenpc.cpp
+++ b/sp/src/game/server/ai_basenpc.cpp
@@ -12429,6 +12429,12 @@ BEGIN_DATADESC( CAI_BaseNPC )
 
 	DEFINE_KEYFIELD( m_flSpeedModifier, FIELD_FLOAT, "BaseSpeedModifier" ),
 	DEFINE_FIELD( m_FakeSequenceGestureLayer,	FIELD_INTEGER ),
+
+	// Jump override keyvalues
+	DEFINE_KEYFIELD( m_jumpUpOverride, FIELD_FLOAT, "JumpUpOverride" ),
+	DEFINE_KEYFIELD( m_jumpDownOverride, FIELD_FLOAT, "JumpDownOverride" ),
+	DEFINE_KEYFIELD( m_jumpDistOverride, FIELD_FLOAT, "JumpDistOverride" ),
+
 #endif
 
 	// Satisfy classcheck
@@ -12539,6 +12545,11 @@ BEGIN_DATADESC( CAI_BaseNPC )
 	DEFINE_OUTPUT( m_OnStateChange,	"OnStateChange" ),
 #endif
 
+	// Change jump height
+	DEFINE_INPUTFUNC( FIELD_FLOAT, "SetMaxJumpUp", InputSetJumpUp ),
+	DEFINE_INPUTFUNC( FIELD_FLOAT, "SetMaxJumpDown", InputSetJumpDown ),
+	DEFINE_INPUTFUNC( FIELD_FLOAT, "SetMaxJumpDist", InputSetJumpDist ),
+
 	// Function pointers
 	DEFINE_USEFUNC( NPCUse ),
 	DEFINE_THINKFUNC( CallNPCThink ),
@@ -17047,3 +17058,21 @@ bool CAI_BaseNPC::IsInChoreo() const
 {
 	return m_bInChoreo;
 }
+
+//-----------------------------------------------------------------------------
+// Purpose: Override the NPC's default jump values
+//-----------------------------------------------------------------------------
+void CAI_BaseNPC::InputSetJumpUp( inputdata_t& inputdata )
+{
+	m_jumpUpOverride = inputdata.value.Float();
+}
+
+void CAI_BaseNPC::InputSetJumpDown( inputdata_t& inputdata )
+{
+	m_jumpDownOverride = inputdata.value.Float();
+}
+
+void CAI_BaseNPC::InputSetJumpDist( inputdata_t& inputdata )
+{
+	m_jumpDistOverride = inputdata.value.Float();
+}
diff --git a/sp/src/game/server/ai_basenpc.h b/sp/src/game/server/ai_basenpc.h
index 71b340cf7e0..80a9877f3ad 100644
--- a/sp/src/game/server/ai_basenpc.h
+++ b/sp/src/game/server/ai_basenpc.h
@@ -2132,6 +2132,11 @@ class CAI_BaseNPC : public CBaseCombatCharacter,
 	void InputIgnoreDangerSounds( inputdata_t &inputdata );
 	void InputUpdateEnemyMemory( inputdata_t &inputdata );
 
+	// Overwrite jump height
+	void InputSetJumpUp( inputdata_t& inputdata );
+	void InputSetJumpDown( inputdata_t& inputdata );
+	void InputSetJumpDist( inputdata_t& inputdata );
+
 	//---------------------------------
 	
 	virtual void		NotifyDeadFriend( CBaseEntity *pFriend ) { return; }
@@ -2488,6 +2493,12 @@ class CAI_BaseNPC : public CBaseCombatCharacter,
 	void				GetPlayerAvoidBounds( Vector *pMins, Vector *pMaxs );
 
 	void				StartPingEffect( void ) { m_flTimePingEffect = gpGlobals->curtime + 2.0f; DispatchUpdateTransmitState(); }
+
+protected: // Jump override variables
+	float				m_jumpUpOverride = 0.0f;
+	float				m_jumpDownOverride = 0.0f;
+	float				m_jumpDistOverride = 0.0f;
+
 };
 
 
diff --git a/sp/src/game/server/ai_basenpc_movement.cpp b/sp/src/game/server/ai_basenpc_movement.cpp
index 142b11e23cd..ed7603bccdb 100644
--- a/sp/src/game/server/ai_basenpc_movement.cpp
+++ b/sp/src/game/server/ai_basenpc_movement.cpp
@@ -297,16 +297,21 @@ bool CAI_BaseNPC::CanStandOn( CBaseEntity *pSurface ) const
 bool CAI_BaseNPC::IsJumpLegal( const Vector &startPos, const Vector &apex, const Vector &endPos, 
 							   float maxUp, float maxDown, float maxDist ) const
 {
-	if ((endPos.z - startPos.z) > maxUp + 0.1) 
+	// Always use the jump override values
+	float localMaxUp = m_jumpUpOverride > 0.0 ? m_jumpUpOverride : maxUp;
+	float localMaxDown = m_jumpDownOverride > 0.0 ? m_jumpDownOverride : maxDown;
+	float localMaxDist = m_jumpDistOverride > 0.0 ? m_jumpDistOverride : maxDist;
+
+	if ((endPos.z - startPos.z) > localMaxUp + 0.1 )
 		return false;
-	if ((startPos.z - endPos.z) > maxDown + 0.1) 
+	if ((startPos.z - endPos.z) > localMaxDown + 0.1 )
 		return false;
 
-	if ((apex.z - startPos.z) > maxUp * 1.25 ) 
+	if ((apex.z - startPos.z) > localMaxUp * 1.25 )
 		return false;
 
 	float dist = (startPos - endPos).Length();
-	if ( dist > maxDist + 0.1) 
+	if ( dist > localMaxDist + 0.1 )
 		return false;
 	return true;
 }
diff --git a/sp/src/game/server/hl2/npc_monk.cpp b/sp/src/game/server/hl2/npc_monk.cpp
index 7f8407713f2..743c225945e 100644
--- a/sp/src/game/server/hl2/npc_monk.cpp
+++ b/sp/src/game/server/hl2/npc_monk.cpp
@@ -744,7 +744,9 @@ int CNPC_Monk::SelectFailSchedule( int failedSchedule, int failedTask, AI_TaskFa
 //-----------------------------------------------------------------------------
 bool CNPC_Monk::IsJumpLegal( const Vector &startPos, const Vector &apex, const Vector &endPos ) const
 {
-	if ( startPos.z - endPos.z < 0 )
+	// `startPos.z - endPos.z < 0` disables jumping up (probably to hack around some silly behavior Valve found in d1_town_02a)
+	// If the mapper is setting jumpUpOverride, they probably want father to jump up
+	if ( startPos.z - endPos.z < 0 && m_jumpUpOverride < 0 )
 		return false;
 	return BaseClass::IsJumpLegal( startPos, apex, endPos );
 }