A turbocharger, comprising: a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing receiving exhaust gas and supplying the exhaust gas to the turbine wheel; a centrifugal compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith, the compressor wheel having blades and defining an inducer portion, the compressor housing having an air inlet wall defining an air inlet for leading air generally axially into the compressor wheel, the compressor housing further defining a volute for receiving compressed air discharged generally radially outwardly from the compressor wheel, the air inlet wall defining an annular space surrounding the air inlet and open to the air inlet at a radially inner end of the annular space; and a compressor inlet-adjustment mechanism disposed in the annular space of the air inlet wall and movable between an open position and a closed position, the inlet-adjustment mechanism comprising a plurality of blades disposed within the annular space, the blades collectively circumscribing an orifice, each blade having an upstream surface relatively farther from and facing away from the compressor wheel and a downstream surface relatively closer to and facing toward the compressor wheel, the blades pivoting about respective pivots radially inwardly from the annular space into the air inlet when the blades are in the closed position so as to cause the orifice to have a reduced diameter relative to a nominal diameter of the inlet; wherein the upstream surface of each of the blades includes a plurality of circumferentially spaced swirl inducers that are structured and arranged to impart swirl to the air passing through the orifice into the compressor wheel. a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing receiving exhaust gas and supplying the exhaust gas to the turbine wheel; a centrifugal compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith, the compressor wheel having blades and defining an inducer portion, the compressor housing having an air inlet wall defining an air inlet for leading air generally axially into the compressor wheel, the compressor housing further defining a volute for receiving compressed air discharged generally radially outwardly from the compressor wheel, the air inlet wall defining an annular space surrounding the air inlet and open to the air inlet at a radially inner end of the annular space; and a compressor inlet-adjustment mechanism disposed in the annular space of the air inlet wall and movable between an open position and a closed position, the inlet-adjustment mechanism comprising a plurality of blades disposed within the annular space, the blades collectively circumscribing an orifice, each blade having an upstream surface relatively farther from and facing away from the compressor wheel and a downstream surface relatively closer to and facing toward the compressor wheel, the blades pivoting about respective pivots radially inwardly from the annular space into the air inlet when the blades are in the closed position so as to cause the orifice to have a reduced diameter relative to a nominal diameter of the inlet; wherein the upstream surface of each of the blades includes a plurality of circumferentially spaced swirl inducers that are structured and arranged to impart swirl to the air passing through the orifice into the compressor wheel.